Turkish President Recep Tayyip Erdogan on Saturday issued a threat to Greece over simmering tensions in the eastern Mediterranean, the day before his forces launch military drills in the region.

Turkey and Greece, both NATO members, have been embroiled in an increasingly heated spat over gas and oil in the region since Turkey deployed an exploration vessel last month. 

"As Turkey and the Turkish people we are ready for every possibility and every consequence," Erdogan said in a televised speech in Istanbul.

Turkish defence officials said they would start five days of military exercises on Sunday in the breakaway republic of northern Cyprus -- an entity recognised only by Ankara.

NATO said this week Greek and Turkish leaders had agreed to take part in technical talks to avoid accidents between their navies.

But Greece later said it had not agreed to the talks, leading to accusations from Turkey that the EU country was shunning dialogue.

Greece and Cyprus have accused Turkey of breaching their sovereignty by drilling in their waters.

But Erdogan made it clear that he would not compromise, saying: "Turkey is ready for any kind of sharing (of energy resources) as long as it is fair."

Turkey on August 10 deployed the Oruc Reis research vessel and an escorting flotilla of warships to the waters between Cyprus and the Greek islands of Kastellorizo and Crete.

The vessel's stay in the contested waters has been extended three times. 

Greece responded by staging naval exercises with several EU allies and the United Arab Emirates, not far from smaller ones Turkey conducted between Cyprus and Crete last week.