Turkey and Greece – both NATO members – are both conducting rival naval exercises off the Greek island of Crete on Tuesday amid rising tension over claims to gas and oil in the Eastern Mediterranean.

Greece announced its exercises on Friday, followed by a NAVTEX released by Turkey on the extension of a seismic research mission south of Kastellorizo by three ships, accompanied by vessels of the Turkish navy until 27 August. It also included a warning for other vessels to avoid the area in its official NAVTEX.

On Friday, Greek officials said that the United Arab Emirates (UAE) would dispatch F-16 fighter jets to Crete for joint training this week.

Germany’s Foreign Minister Heiko Maas is being sent to Athens and Ankara on Tuesday in an effort to reduce the escalating tension in the Eastern Mediterranean.

Mr Maas will meet with Greek Prime Minister Kyriakos Mitsotakis before talks in Ankara amid escalating tension.

READ MORE: Turkey extends seismic survey in Eastern Mediterranean as tension with Greece escalates

Turkish President Recep Tayyip Erdogan on Tuesday responded to the counter-NAVTEX issued by Greece with fresh criticism. He warned Greece that it would be solely responsible for the “damage it would suffer” in the region.

“Greece has no right to issue NAVTEX for the region where we have done it. I think it would be useful for our Greek neighbours to understand that those who dragged Greece in front of the Turkish navy, will not reappear in a possible problem that will arise in the future. Today’s statement by Greece endangers the coastal and maritime safety of all ships in the region,” he said.

Greek Government Spokesman Stelios Petsas said, “Greece is responding calmly and with readiness both on a diplomatic and on an operational level. And with national confidence it does everything needed to defend its sovereign rights.”

Greece’s agreements with Italy and Egypt on maritime zones were tabled in in the parliament’s Standing Committee on National Defense and Foreign Affairs on Monday afternoon.

READ MORE: Turkey extends seismic survey in Eastern Mediterranean as tension with Greece escalates

“We cannot imagine any responsible political force, especially the main opposition, rejecting these agreements. They are therefore called upon to reveal their stance: yes or no,” he said.

Mr Petsas also noted that the fence at the Evros borders with Turkey will be extended to points suggested by the armed forces and the police. The project has been assumed jointly by four of Greece’s five largest construction companies and it will be ready in 5-8 months from today, he said.

On Turkish aggression, he said that “Turkey has a long way to go” to prove that President Recep Tayyip “Erdogan means what he says. If a de-escalation of the tension occurs, we are ready to go into talks at any time.” He said talks with the neighboring country would work in the framework of the 2016 exploratory talks that were interrupted by Turkey.