Turkey has begun surveying for oil and gas in the eastern Mediterranean, in an area claimed by Greece.
Turkish Energy and Natural Resources Minister Fatih Donmez tweeted that the Oruç Reis research vessel had lowered seismic cables into the sea.
Greece called on Turkey to remove its ships from the area, but Turkey refused, AP reported. According to the report, Greek Foreign Minister Nikos Dendias is scheduled to meet with U.S. Secretary of State Mike Pompeo on Friday to discuss the matter.
The move comes amid heightened tensions between Ankara and Athens over oil and gas-exploration rights, and both countries sent warships to monitor the Turkish research ship.
Israel, which approved a deal in July with Cyprus, Greece and Italy for the EastMed pipeline—to transport natural gas to Europe, without Turkish participation—is closely monitoring Ankara’s moves in the Mediterranean. Israel expressed its “full support and solidarity” with Cyprus last month, in the wake of Turkish natural gas drilling operations off the coast of Cyprus, which Nicosia claims violate its sovereignty.