ATHENS, Greece — Greece's foreign minister accused Turkey on Wednesday of undermining stability and security in the eastern Mediterranean and causing problems with all of its neighbors, while also violating Greek airspace and territorial waters daily.

Nikos Dendias slammed Turkey's actions in recent months in the Aegean Sea, which separates the two countries, saying Ankara must "abstain from its illegal gunboat diplomacy." Dendias was speaking during a visit to Greece's northeastern border with Turkey, and was accompanied by the European Union's foreign policy chief.

NATO allies and neighbors Greece and Turkey have long had difficult relations, and the two countries have come to the brink of war three times since the 1970s. Divided over a series of issues, including territorial disputes in the Aegean, relations have become increasingly strained in recent months.

Earlier this year, Turkish President Recep Tayyip Erdogan declared the borders with Europe were open to migrants living in Turkey who wanted to head into the European Union. Although Turkey also shares a border with EU member Bulgaria, it was only on the Greek land border crossing that tens of thousands of migrants gathered, demanding to be allowed to cross. 

Dendias described the action as "the exploitation, on the part of Turkey, of the hopes of tens of thousands of civilians for a better life … misled through a disinformation campaign orchestrated by Turkish officials at the highest level."

Dendias and EU foreign policy chief Josep Borrell toured the border crossing area in the Evros region where the migrants had gathered in late February.

"It's very clear that we are determined to protect the external borders of the European Union and to strongly support Greece's sovereignty," Borrell said. 

Borrell said his visit to Greece had been planned but had been pushed forward after recent incidents involving Turkey "in order order to show our solidarity and to show how much we share your concerns."

Greece and Turkey are also in dispute over oil and gas exploratory drilling rights in the Mediterranean, with Greece, Cyprus and Egypt outraged at a Turkish agreement with the U.N.-recognized government in Libya laying claim to rights of a swathe of the Mediterranean that they say infringes on their sovereign rights.