Greece had to scramble fighter jets to intercept a passenger plane that entered the Athens Flight Information Region (FIR) without identifying itself, according to reports in local media.
The plane, reportedly a Delta airliner flying from France to Kuwait, entered the Athens FIR at 7.10 p.m. on Thursday.
Reports said the pilots failed to respond to repeated calls from Greek civil aviation authorities.
At 7.38 p.m. two F-16 fighter jets were dispatched, intercepting the plane 7 miles east of the Aegean island of Santorini.
Radio communications were reportedly re-established at 7.55 p.m. and the aircraft left the Athens FIR a few minutes later.
No more information was made available about the incident.