The Greek prime minister has accused Turkey of "harassing" his helicopter with fighter jets as he travelled to an independence day celebration.
Alexis Tsipras said his helicopter was forced into "low manoeuvres" on Monday when Turkish jets entered Greek airspace.
The prime minister accused Turkey of "foolish actions that have no meaning".
Turkish security forces rejected the accusations, insisting the jets were carrying out a routine mission.
"The Greek military intercepted the forces that violated the national airspace," Mr Tsipras said in a speech on the small eastern Aegean island of Agathonisi, located close to the Turkish mainland, to mark independence day.
The national holiday celebrates Greece's uprising against the Turkish Ottoman Empire in 1821.
"I had the honour of welcoming you here in Agathonisi and some fighter aircrafts of the Turkish air force, perhaps for the day, wanted to participate in the celebration," the prime minister said.
"What do they think they are doing?"
Mr Tsipras said that he was committed to co-operation with Turkey but that Greece would always protect its national integrity.
Turkey has denied claims of harassment.
Turkish state-funded Anadolu news agency quoted the security forces as saying that the planes were "conducting their regular mission".
Relations between the two countries have been strained for decades over territorial disputes in the Aegean.
But Mr Tsipras and Turkish leader Recep Tayyip Erdogan have made efforts to improve relations. In 2017, Mr Erdogan became the first Turkish head of state to visit Greece for 65 years.