Greece on Tuesday urged the United Nations to condemn a disputed maritime jurisdiction deal between Turkey and Libya as "disruptive" to regional peace and stability, a government spokesman said.
Greece "wants the deal to be brought to the attention of the UN Security Council so it can be condemned," Stelios Petsas told a news conference.
Turkish President Recep Tayyip Erdogan last month met with the head of the Tripoli-based Government of National Accord (GNA), Prime Minister Fayez al-Sarraj, to sign agreements on security and military cooperation, as well as maritime jurisdictions.
Part of the deal sets a maritime boundary between the two countries, which Greece says fails to take into account the island of Crete.
Petsas on Tuesday said Athens had sent separate letters on the issue to UN chief Antonio Guterres and the UN Security Council, arguing that the deal was contracted "in bad faith" and "is null as it was not approved by the Libyan parliament", which is controlled by a rival faction hostile to the Tripoli-based government.
On Monday, Erdogan said he envisaged joint energy exploration activities with Libya in the eastern Mediterranean.
Turkey already has ships searching for oil and gas off Cyprus, which has fuelled tension with the European Union.
The Greek government last week expelled the Libyan ambassador over the deal with Turkey and has sought to have the deal dismissed at international level.
Greek Foreign Minister Nikos Dendias spoke with EU partners over the weekend and has been in close contact with regional ally Egypt.
Greek Prime Minister Kyriakos Mitsotakis is to meet with US Ambassador Geoffrey Pyatt later Tuesday, his office said, ahead of a White House visit on January 7.
Dendias said Libya had been "blackmailed" by Turkey to sign the deal.
The foreign minister told ANT1 TV the move was "clearly" related to setbacks suffered by the UN-recognised government in Tripoli in its struggle against eastern Libya strongman Khalifa Haftar.
Libya has been mired in chaos since a NATO-backed uprising that toppled and killed dictator Moamer Kadhafi in 2011.
Libyan parliament head Aguila Saleh Issa, an ally of Haftar, is expected in Athens for talks this week.
Greece and Turkey are also at odds over the high number of asylum-seekers arriving on Greek islands, and exploitation of energy reserves in the eastern Mediterranean.