Sticking to a hard line even while set to conduct talks with Greece, Turkey plans to go ahead with drilling for oil and gas off Greek islands as it's already doing off Cyprus, undeterred by threats of possible European Union sanctions.

The EU's leaders, in a two-day meeting with Turkish officials that began Oct. 1, said hard penalties would be imposed if the talks with Greece fail or if Turkey again sends an energy research vessel and warships into Greek waters.

Turkey would be more determined to protect its territorial rights in the Eastern Mediterranean if the EU imposes sanctions, a Turkish Foreign Ministry official not named told the Reuters news service.

The senior official said sanctions would not stop Turkey, which is already ignoring soft penalties for drilling off Cyprus, adding that just having them on the table could undercut coming talks in Ankara with Greek officials.

EU leaders repeated their same tactic of warning Turkey after Cyprus pulled back a planned veto against sanctions for Belarus over rigged Presidential elections, no longer tying its support for penalties to Turkish sanctions.

Sanctions could come as soon as December if "provocations" have not stopped, the EU statement said, enough to satisfy Cypriot President Nicos Anastasiades and Greek Prime Minister Kyriakos Mitsotakis, who had objected to language soft on Turkey.

Greece and Turkey had been at near-conflict levels for weeks before Turkish President Recep Tayyip Erdogan withdrew an energy research vessel and warships from near the Greek island of Kastellorizo to give diplomacy a chance.

Two Turkish and Greek frigates collided at sea in August near one of Turkey's exploration vessels but tension has cooled after the countries, both members of NATO, said they would resume "exploratory talks" that ended in 2016.

The talks are an effort "to bring Greece into dialogue and finally Greece agreed to that, and we hope to resume those soon," likely this month, the Turkish official said.

But "if the EU applies sanctions this will not deter us. On the contrary this would increase our resolve and would be a negative stance on the part of the European Union," he said.

"We will continue our offshore program as we have been doing. Sanctions are not the right way (and) will not deter us to protect our rights to our continental shelf and also the rights of the Turkish Cypriots," the official added.