Greece lodged objections with the UN over an accord between Libya and Turkey mapping out maritime boundaries as a violation of international law, the Greek government said.
Greece expelled the Libyan ambassador in response to the accord last week, irate at a pact which skirts the Greek island Crete and infringes, in Athens’s view, on its continental shelf.
“This agreement was compiled in bad faith,” government spokesman Stelios Petsas said.
“It violates the UN Law of the Sea. The sea zones of Turkey and Libya do not meet, nor is there a sea border between the two states,” Petsas said.
A row over eastern Mediterranean gas reserves offshore has become increasingly shrill with countries in the region jostling to stake claims.
Turkey has had a long-running disagreement with ethnically split Cyprus over reserves around the island.
Greece and Turkey are at loggerheads over mineral rights in the Aegean Sea and Greece accused the internationally-recognised Libyan government of deceiving Athens by negotiating the maritime accord with Ankara.
It carves out a sea corridor of maritime boundaries at the closest points between Libya and Turkey potentially clearing the way for oil and gas exploration there.
Turkish President Tayyip Erdogan, speaking to Turkish state broadcaster TRT Haber, said the agreement was in line with international law.
Petsas said Greece asked its EU partners to formulate a framework of sanctions on Turkey and Libya if the agreement is not rescinded.
Turkey faces sanctions for its actions around Cyprus, split in a Turkish invasion in 1974 after a Greek-inspired coup.
Peace talks on the island have been in limbo since UN-led efforts collapsed in 2017 and tension between Turkey and Greece inevitably rubs off on the island.
On Tuesday, Greek and Turkish Cypriot leaders, Nicos Anastasiades and Mustafa Akinci, cancelled plans to attend a reception hosted by the UN in Nicosia.