In a further escalation of tensions in the Aegean, a chief advisor to Turkish President Recep Tayyip Erdogan has issued a direct threat to Greek Prime Minister Alexis Tsipras, his ministers and other Greek officials not to set foot on the islets of Imia whose sovereignty Ankara disputes.

In comments on Turkish television, referring to Imia over which Greece and Turkey came close to war in 1996, Yigit Bulut said that Athens will "feel the anger of Turkey, worse than that in Afrin," referring to the Kurdish-controlled enclave in Syria where Turkish troops have engaged.

"We will break the arms and legs of any officers, of the prime minister or of any minister who dares to step onto Imia in the Aegean," Bulut said, using unusually strong language.

His comments came amid a spike in Turkish air space violations in the Aegean and an escalation of provocative rhetoric by Turkish officials over issues relating to territory in the Aegean.

Earlier this week, the US Ambassador to Athens Geoffrey Pyatt expressed his concern over the possibility of an "accident" happening between Greece and Turkey in the Aegean.

In an interview with Skai television, the American envoy referred to coast guard maneuvers in the eastern Aegean, where Greek and Turkish vessels often come very close to one another.

His comments followed an incident involving a Turkish coast guard vessel which skimmed a Greek gunboat off the islets of Imia.