Greece-Turkey ties are already strained over Ankara's gas exploration in the eastern Mediterranean, although they held direct talks last month for the first time in nearly five years.

In the dispute's latest chapter, Turkey last week sent the Cesme research vessel into international waters near some Greek islands, prompting Athens to lodge a diplomatic protest.

On Tuesday, a Turkish defence ministry source said four Greek F-16 fighter jets engaged in "provocative action" and "harassed the Cesme vessel in the northern Aegean's international waters".

Turkish Defence Minister Hulusi Akar told reporters that a "necessary response was given".

"Unfortunately, this is one of the frequent harassments by our Greek neighbours," Akar said in Ankara.

The Turkish defence source said one of the Greek planes dropped a chaff cartridge two nautical miles (3.7 nautical kilometres) away from the Turkish ship.

The cartridges are used to confuse or disable an opponent's radar.

The Greek defence ministry said its airforce was conducting a military exercise some distance from the Turkish vessel and denied any harassment.

"No Greek fighter jets flew near the Turkish vessel," Greek defence ministry said.

The scene was set for tensions when Turkey announced last Monday the Cesme ship would conduct a hydrographic survey from February 18 until March 2.

Greek government spokesman Christos Tarantilis called it "an unnecessary move which does not help positive sentiment".

Akar defended Turkey's actions, insisting the survey was "completely hydrographic, technical" and saying Greece had conducted similar work in the past.

"Turkey has always been on the side of dialogue," Akar said.

Pushed by the European Union to hold talks, Turkish and Greek officials last month held exploratory talks in Istanbul, the first since 2016.

There was no breakthrough and the two sides only agreed for talks to resume in Athens.

The Greek foreign ministry said last week the next round in Athens could be held in early March, pending a reply from Turkey.

The crisis over the eastern Mediterranean re-erupted last summer when Ankara sent a research ship into waters claimed by Greece.