The row over gas exploration in the eastern Mediterranean saw the two NATO countries stage rival military drills in August in strategic waters between Cyprus and the Greek island of Crete.

Greece claims rights over the waters around its island of Kastellorizo but Turkey says its longer coastline makes the territory a legitimate area for its vessels to explore.

The Turkish navy said the Oruc Reis ship will carry out activities in the region, including the south of Kastellorizo, until October 22 in a message sent to the maritime alert system NAVTEX late on Sunday.

The vessel will be joined in the latest "seismic survey" mission by two other ships called Ataman and Cengiz Han, the message said.

Turkish Energy Minister Fatih Donmez delivered a defiant message via Twitter on Monday that Turkey "will continue to search, dig and protect our rights".

"If there is (natural gas), we will absolutely find it," he said.

But Greece's foreign ministry on Monday lambasted the move as a "direct threat to regional peace and security" and accused Turkey of being unreliable.

The ministry added in a statement that Ankara did not "sincerely desire dialogue".

Ankara first deployed the Oruc Reis and warships to disputed waters on August 10 and extended the mission, ignoring repeated calls to stop by Greece and the European Union.

- 'Provocative actions' -

Turkish Defence Minister Hulusi Akar later on Monday hit out at Greece, stressing that Ankara's actions in the Aegean and Mediterranean were "not a threat to anyone".

"They are doing everything they can to increase tensions. They are attempting provocative actions. We desire our neighbours stay away from such actions," Akar told reporters in Ankara.

"Bullying and impositions won't make Turkey act differently," Turkey's ruling party spokesman Omer Celik tweeted, as he insisted Turkey was always "open to negotiating".

The Oruc Reis was pulled back to shore last month in what many hoped was a sign the two sides could resolve the issue through dialogue.

Turkish President Recep Tayyip Erdogan said at the time that the withdrawal was designed to give diplomacy a chance.

But Turkish officials also insisted the ship was in port for planned maintenance and would return to the eastern Mediterranean to continue its work.

In his tweet on Monday, Donmez said maintenance work was finished and the ship could now restart its scan of the Mediterranean.

- Sanctions threat -

The announcement dashed hopes raised when Turkey and Greece agreed to exploratory talks last month after diplomatic efforts led by Germany to defuse the crisis.

The talks had been stalled since 2016 and the expectation was for their resumption in Istanbul but no exact date was given.

The Turkish and Greek foreign ministers also met last week on the sidelines of a security forum in Slovakia's capital Bratislava in the highest-level talks since tensions began.

The ministers had agreed that a date should be set for the start of exploratory talks, according to a Greek foreign ministry source.

At a summit earlier this month, the European Union threatened sanctions if Turkey failed to stop what the bloc says is illegal drilling and energy exploration activities in waters claimed by Cyprus and Greece.

The German foreign minister is expected to visit Ankara on Wednesday, according to Turkish state broadcaster TRT, where the eastern Mediterranean will be high on the agenda.