ATHENS, Greece (AP) — A Greek air force fighter jet crashed into the Aegean Sea on Thursday after returning from a patrol, killing the pilot, Defense Ministry officials said.

The officials said the single-seater Mirage 2000-5 crashed north of the island of Skyros in the central Aegean. They gave no information about the possible cause of the crash.

Aegean patrolling has intensified in recent weeks amid a spike in tensions between Greece and Turkey and near-daily interceptions and mock dogfights in disputed airspace around Greek islands near Turkey's coastline.

The pilot's death was announced by Defense Minister Panos Kammenos after Greek navy ships and army helicopters had searched for him.

"A Greek pilot joins the pantheon of heroes. He fell in the defense of our national sovereignty and territorial integrity," Kammenos said on Twitter.

Turkish Prime Minister Binali Yildirim called his Greek counterpart Alexis Tsipras to convey his condolences and those of Turkish President Recep Tayyip Erdogan for the pilot's death, Tsipras' office said.