In-Depth Analysis· Seville Map Türkiye Libya memorandum 2019 maritime boundaries explained

The Seville Map and the Türkiye–Libya Memorandum: Who Is Right on Maritime Boundaries?

Is the Seville Map legally binding? Is the 2019 Türkiye–Libya memorandum valid? A source-based explainer of maritime boundaries, island effect and equity.

B&B

By Borders & Blocs Editorial Team

Published: October 26, 2026

⏱ 9 min read (1,844 words)

Executive Summary & Key Facts

The Seville Map is a 2020 academic study, not a treaty, court ruling or adopted EU act, so it has no binding force on any state.
Maritime delimitation is a matter for coastal states, courts and tribunals under UNCLOS Articles 74 and 83 and customary law; it is not a competence transferred to the European Union.
The 27 November 2019 Türkiye–Libya memorandum is a bilateral delimitation of continental shelf and EEZ claims; Greece, Cyprus, Egypt and the EU contest it, while Ankara says it rests on equity and opposite coasts.
International case law, from North Sea Continental Shelf (1969) to Romania v. Ukraine (2009), shows that small islands often receive reduced or no effect in delimitation, but no ruling has settled the Kastellorizo–Crete–Rhodes question.
Under the law of treaties, a bilateral agreement cannot create obligations for third states, which cuts both ways: the memorandum cannot bind Greece, and Greece's islands-based claims cannot bind Türkiye or Libya.

Why It Matters

The Seville Map is not legally binding: it is a technical study that shows one maximalist reading of island entitlements, and no international court has adopted it. The 27 November 2019 Türkiye–Libya memorandum is a bilateral maritime delimitation accord that is effective between its two parties but cannot bind third states, and its validity is contested politically and, in part, domestically in Libya. The real legal question behind both documents is how much weight small islands near a long mainland coast should carry in delimitation.

Background

The legal framework

Delimitation between states with opposite or adjacent coasts is governed by Articles 74 and 83 of the 1982 UN Convention on the Law of the Sea (UNCLOS), which require agreement 'on the basis of international law' to reach 'an equitable solution'. Greece, Cyprus, Egypt and Libya are UNCLOS parties. Türkiye is not, and argues that customary law and the equity principle govern its maritime claims. Article 121 says islands generate maritime zones, but rocks that cannot sustain human habitation or economic life have no EEZ or continental shelf. States and courts read that provision differently.

Case law on islands and proportionality

Courts and tribunals have repeatedly adjusted provisional lines to avoid disproportion between coast length and maritime area. The best-known decisions are:

North Sea Continental Shelf (ICJ, 1969): delimitation must follow equitable principles; geography is not to be 'completely refashioned'.
Anglo-French Arbitration (1977): the Channel Islands were enclaved, and the Scilly Isles received only half effect.
Tunisia/Libya (ICJ, 1982): the Kerkennah Islands received half effect.
Libya/Malta (ICJ, 1985): the court stressed proportionality and gave Malta a reduced line.
Romania v. Ukraine (ICJ, 2009): Serpents' Island, a small feature, had no effect on the delimitation line.
Bangladesh/Myanmar (ITLOS, 2012): St Martin's Island was given no effect beyond its territorial sea.
Nicaragua v. Colombia (ICJ, 2012): small Colombian islands were enclaved, with limited effect.

These decisions do not say that islands never count. Greece points out that inhabited islands such as Crete and Rhodes are large and generate zones under Article 121(2). Nobody has ruled on the specific geography of the Eastern Mediterranean, so both sides cite the same body of case law.

Chronology

Date	Event
2003	Cyprus–Egypt EEZ agreement, which Türkiye says overlaps its continental shelf
2004 onward	Türkiye lodges continental shelf positions with the UN
21 Sep 2011	Türkiye–TRNC Continental Shelf Delimitation Agreement
27 Nov 2019	Türkiye and Libya's UN-recognised Government of National Accord sign the maritime memorandum (and a separate security memorandum)
12 Dec 2019	European Council conclusions call the memorandum contrary to the law of the sea and unable to produce legal consequences for third states
2020	Seville study and map circulated; Italy–Greece and partial Egypt–Greece EEZ agreements signed
18 Mar 2020	Türkiye registers the outer limits of its continental shelf with the UN
16 Apr / 12 Jun 2025	Türkiye announces its Marine Spatial Planning, then registers it with IOC-UNESCO

Key Players & Positions

The Seville Map and the EU

The 'Seville Map' takes its name from a 2020 study by researchers at the University of Seville. It gives full effect to Greek islands including Kastellorizo (Meis), Rhodes, Karpathos and Crete, which leaves Türkiye a narrow maritime strip in the Gulf of Antalya. Greek officials cite it as consistent with UNCLOS. To our knowledge, it has not been adopted as an act of the Council or Commission. The EU is a party to UNCLOS, but delimitation between states is not among the competences its members transferred to it, so only the coastal states concerned, or a court or tribunal they seize, can draw boundaries. The EU does take political positions. The European Council has repeatedly voiced solidarity with Greece and Cyprus and criticised Turkish activities in disputed waters.

Greece and the Greek Cypriot administration

Athens argues that all inhabited islands, Kastellorizo included, generate a full continental shelf and EEZ under UNCLOS Article 121 and customary law, and that delimitation with Türkiye should be by median line, ideally through the ICJ. Athens also says the Libya memorandum ignores Crete and other islands, and that Türkiye and Libya have no maritime border once those islands are counted. Greece's partial EEZ agreements with Italy (2020) and Egypt (2020) are presented as lawful delimitations. The Republic of Cyprus, an UNCLOS party, holds that its 2003 agreement with Egypt and its 2007 and 2010 agreements with Lebanon and Israel are valid, and that it is entitled to exploit resources for the whole island.

Egypt

Cairo rejects the 2019 memorandum as null for third parties, saying it affects Egyptian rights, and signed its own partial delimitation with Greece in August 2020. Egypt's formal position is based on UNCLOS and on its 2003 agreement with Cyprus. Relations between Cairo and Ankara have improved since 2023, but no delimitation between them exists.

Libya

The memorandum was concluded by Libya's internationally recognised Government of National Accord, led by Fayez al-Sarraj. Rival authorities in eastern Libya, including the House of Representatives in Tobruk, rejected it. Critics argue it was not properly approved under Libya's political arrangements. Successive Tripoli governments have not repudiated it, and the question of its status in domestic law remains a live one.

🇹🇷 Official Policy · Primary Sources · Treaty Texts

Türkiye's Position

Ankara argues that the issue is one of equity, not of any one map. Its position, as set out by the Republic of Türkiye Ministry of Foreign Affairs and the Presidency, rests on these points:

Equity and proportionality govern delimitation. According to the Turkish Foreign Ministry, a delimitation must achieve an equitable result, and islands cannot cut off the coastal projection of a mainland with the longest coastline in the Eastern Mediterranean (about 870 km / 540 miles). Ankara cites North Sea Continental Shelf, the Anglo-French award, Libya/Malta and Romania v. Ukraine in support. Kastellorizo lies roughly 2 km off the Turkish coast and more than 500 km from mainland Greece.
The Seville Map has no legal standing. Ankara argues that the map is a maximalist study that tries to confine Türkiye to the Gulf of Antalya, and that the EU has no jurisdiction over maritime delimitation under the pretext of Union solidarity.
The 2019 memorandum is a valid bilateral agreement between opposite coasts. Türkiye says the line was drawn between the coasts of two states with sovereign treaty-making capacity, using the equity principle, and that it does not affect third states' rights since it covers only areas lying on the Turkish and Libyan sides of the line. Under the law of treaties (Vienna Convention, Article 34), agreements bind only their parties. Türkiye applies the same reasoning to the 2003 Egypt–Cyprus agreement, which it says violates its continental shelf.
Turkish Cypriots have equal rights over the island's resources. Ankara and the TRNC point to the 21 September 2011 Continental Shelf Delimitation Agreement and to proposals for a joint committee and revenue sharing (2011, 2012, 2019). They argue that no hydrocarbon arrangement excluding Turkish Cypriots is legitimate.
Dialogue and registration. Türkiye registered its continental shelf outer limits with the UN on 18 March 2020 and its Marine Spatial Planning with IOC-UNESCO on 12 June 2025. President Erdoğan's 2020 proposal for an Eastern Mediterranean conference involving all coastal states and the Turkish Cypriots remains on the table.

For the wider doctrine, see Eastern Mediterranean and the Blue Homeland: Türkiye's Maritime Jurisdiction Explained and The Cyprus Issue: 1960 Treaties, 1974 and the Case for a Two-State Solution.

Source Comparison

Question	Greek / Greek Cypriot / EU sources	Turkish official sources	Neutral reading
Is the Seville Map binding?	Presented as scientific support for UNCLOS-based island entitlements	Rejected as a maximalist, non-binding study	Not binding: no treaty or judgment adopts it
Who can delimit?	Courts or bilateral agreement; EU backs members politically	States only; the EU has no competence	Only states, courts and tribunals delimit
Role of islands	Full effect for inhabited islands (Article 121(2))	Reduced or no effect where they distort the mainland coast	Case law varies by size, location and proportionality
2019 memorandum	Violates third-state rights; ignores Crete and others; 'no legal consequences' (European Council, 12 Dec 2019)	Valid bilateral delimitation between opposite coasts	Effective between the parties; cannot bind third states; line itself contested
Legal basis	UNCLOS Articles 74, 83, 121	Customary law and equity; Türkiye is not an UNCLOS party	Court practice treats much of delimitation law as customary

Our reading: the strongest claim each side can make is narrower than its official rhetoric. Greece cannot show that a map or EU conclusions fix a boundary. Türkiye cannot show that a bilateral agreement settles a boundary against Greece or Egypt. Only agreement, or adjudication, can do that. For how we handle sources, see Editorial Principles and Primary Source Standards.

EEZ (Exclusive Economic Zone): a zone of up to 200 nautical miles in which a coastal state has sovereign rights over resources.
Continental shelf: the seabed and subsoil extending from a state's coast, over which the state has sovereign rights to explore and exploit natural resources.
Equity principle: the rule that delimitation should produce an equitable result, assessed through coastal geography and proportionality.
Island effect: the degree to which an island shifts a boundary line. It can be full, partial or nil.
Pacta tertiis (Vienna Convention, Article 34): a treaty creates neither obligations nor rights for third states without their consent.
Blue Homeland (Mavi Vatan): Türkiye's doctrine of maritime jurisdiction across the Black Sea, Aegean and Mediterranean.

Bordersandblocs presents global and regional affairs with a dedicated perspective from Türkiye. Sections marked 'Türkiye's Position' reflect official Turkish policy and legal doctrines as stated by Turkish primary sources.

Cross-Publication Dossiers & Sister Desk Perspectives

For complementary primary-source analysis across our specialist editorial network, consult:

Region Scope: The 2019 Türkiye–Libya Maritime Memorandum Explained: Legal Basis, Objections and Impact — What the 27 November 2019 Türkiye–Libya maritime memorandum says, the equity and coastline argument, and objections from Greece, Cyprus, Egypt and the EU.
The Political Axis: The 2019 Türkiye–Libya Maritime Memorandum: What It Says and Why It Matters — Türkiye Libya maritime memorandum 2019 explained: what the 27 Nov 2019 MoU delimits, its legal basis, and why Greece, Egypt, Cyprus and the EU object.
Horizon of Nations: The 2019 Türkiye–Libya Maritime Memorandum: Legal Basis, Objections and Context — Türkiye Libya maritime memorandum 2019 explained: equity principle, UN registration, and objections from Greece, Egypt, Cyprus, the EU and Libya's debate.

Frequently asked questions

Is the Seville Map legally binding?

No. It is a 2020 academic study by researchers at the University of Seville, not a treaty, a court judgment or a Council or Commission act. Maritime boundaries can only be fixed by agreement between the states concerned or by a court or tribunal they seize.

Does the EU have the authority to draw maritime boundaries?

No. Delimitation between coastal states is not a competence transferred to the EU. The Union can express political solidarity with Greece and Cyprus, as in the European Council conclusions of 12 December 2019, but those conclusions do not delimit any zone.

Is the 27 November 2019 Türkiye–Libya memorandum valid?

It is effective between Türkiye and Libya's then UN-recognised government, but it cannot bind third states under the law of treaties. Greece, Cyprus, Egypt and the EU contest it, and some Libyan authorities questioned its approval. Whether the line is equitable given Crete and other Greek islands has not been tested before a court.

What do international courts say about islands in delimitation?

Courts have given small islands reduced or no effect in several cases, such as Serpents' Island in Romania v. Ukraine (2009), St Martin's Island in Bangladesh/Myanmar (2012) and the Scilly Isles in the 1977 Anglo-French award. They have not said that islands are irrelevant, and large inhabited islands generally generate full zones. Each outcome depends on geography and proportionality.

Why does Türkiye say Kastellorizo should not generate a large zone?

Ankara argues that Kastellorizo lies about 2 km off the Turkish mainland and more than 500 km from mainland Greece, so giving it full effect would cut off the projection of Türkiye's long coast. Greece replies that Article 121 and customary law grant inhabited islands full zones. The disagreement is why both sides say they would negotiate, but on different terms.

Is Türkiye bound by UNCLOS?

Türkiye is not a party to UNCLOS and argues that customary international law and the equity principle apply. Greece, Cyprus, Egypt and Libya are parties. Many UNCLOS provisions are considered customary, which is why both sides cite the same case law.

Cross-Publication Perspectives & Cited Research

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