Tensions over energy resources in the eastern Mediterranean have risen sharply after Turkey said it would “exercise its sovereign rights” to drill off Cyprus in flagrant defiance of warnings from western allies.

As the dispute over potential gas reserves intensified, Ankara insisted its state-of-the-art drilling ship, the Fatih, and its support vessels would begin operations in waters viewed by the EU as being within the island’s exclusive economic zone, according to The Guardian.

“Turkey does not recognise the unilateral and illegitimate exclusive economic zone claims of the Greek Cypriots,” its foreign minister, Mevlüt Çavuşoğlu, announced in a letter released by the state-run Anadolu news agency. “Third parties should refrain in taking sides in overlapping maritime boundary claims and they should not act as if they are in a court in rendering judgement on bilateral maritime boundaries.”