Defense ministry officials in Greece say an air force fighter jet has crashed into the eastern Aegean Sea after returning from a patrol, and it is unclear whether the pilot survived.

The officials told state-run television that the Mirage 2000-5 crashed Thursday north of the island of Skyros. They gave no information about the possible cause of the crash.

Patrolling has intensified in recent weeks amid a spike in tensions between Greece and Turkey and near-daily mock dogfights in disputed airspace.

Greek navy ships and army helicopters are searching for the missing pilot.