ATHENS — Greece's foreign minister headed to New York on Friday for talks with the United Nations secretary-general as tensions between Greece and Turkey escalate over maritime boundaries and energy resources in the eastern Mediterranean.

Foreign Minister Nikos Dendias' meeting with U.N. Secretary-General Antonio Guterres will focus on "issues of international and regional interest, with an emphasis on current developments in the eastern Mediterranean and the Cyprus issue, as well as the role of the U.N.." the Greek Foreign Ministry said.

Neighbors and NATO allies Greece and Turkey have been locked in a tense standoff in the eastern Mediterranean, where Turkey is prospecting the seabed for energy reserves in an area Greece claims as its own continental shelf. Ankara says it has every right to prospect there and accuses Greece of trying to grab an unfair share of maritime resources.

Greek Prime Minister Kyriakos Mitsotakis said Dendias would be delivering a letter from him to Guterres detailing what he said was Turkey's illegal activity in the region.

Speaking with China's top diplomat Yang Jiechi in Athens, Mitsotakis said Greece faces aggression from Turkey and "actions that dispute every rule of the U.N. charter, with a rhetoric that distorts history and changes geography, undermining legality and with actions that are endangering security in the entire Mediterranean."

Since Turkey dispatched a vessel accompanied by warships to do expoaratory research in the disputed area, Greece's armed forces have been placed on alert. Both countries sent warships to the area and carried out live-fire exercises between the islands of Crete and Cyprus and Turkey's southern coast.

Simulated dogfights between Greek and Turkish fighter pilots have multiplied over the Aegean Sea and the eastern Mediterranean. A Turkish and a Greek frigate collided last month, reportedly causing minor damage to the Turkish frigate but no injuries.

The current crisis is the most serious in the two countries' relations in decades. The neighbors have come to the brink of war three times since the mid-1970s, including once over maritime resources in the Aegean Sea.

Mitsotakis said Friday that Greece supports good neighborly relations, and he noted that Turkish President Recep Tayyip Erdogan has said he is open to dialogue.

"And to this I reply with six clear words: The provocations stop, the dialogue starts," Mitsotakis said. 

On Thursday, NATO Secretary General Jens Stoltenberg said the two sides had agreed to start "technical talks" to reduce the risks of military "incidents and accidents." 

But Athens quickly denied any such agreement, saying Turkey must first withdraw its ships from the area where it is carrying out gas and oil prospecting. Ankara said it backed Stoltenberg's initiative for military and technical talks and called on Greece to do the same.

Turkish Foreign Minister Mevlut Cavusoglu accused Greece of "lying" about the NATO initiative, saying Stoltenberg had consulted with Ankara and Athens — and both agreed to the technical talks— before making his announcement.

"Greece has refuted the NATO secretary general," Cavusoglu told reporters. "But it isn't the NATO secretary general who is lying, it's Greece itself who is lying….Greece has once again shown that it does not favor a dialogue."

Meanwhile, the spokesman for Turkey's ruling party, Omer Celik, said the European Union could no longer count on Turkey's cooperation in stemming the flow of migrants and refugees to Europe if it goes ahead with plans to sanction Turkey over its exploration operations in the eastern Mediterranean.

"I don't expect things to come to the point of sanctions. The EU should not expect cooperation on refugees after that time," Celik said in an interview with Turkey's NTV news channel. "They should not think that they can sanction (Turkey) in the eastern Mediterranean and continue to cooperate in other areas."

Earlier this year, tens of thousands of migrants gathered at Turkey's border with Greece, demanding to be allowed to cross, after the Turkish president declared the borders with Europe open to migrants wanting to head into EU nations.