Turkey accused Syria on Sunday of shooting down a military plane in international airspace without warning and called a Nato meeting to discuss a response to Syrian President Bashar al-Assad. Amid growing acrimony between the once-friendly neighbours, Syria said its forces had shot dead "terrorists" infiltrating its territory from Turkey, which along with Western and Arab nations has backed the cause of Syrians fighting Assad.

Turkey's foreign minister Ahmet Davutoglu said the search for two missing pilots was still under way, in coordination with the Syrian authorities. He denied it was a "joint" operation.

He told state broadcaster TRT the plane had been clearly marked as Turkish and dismissed Syria's assertion it had not identified the aircraft before opening fire.

Davutoglu said he also planned to set out Turkey's case before the United Nations Security Council where Western powers are seeking, in the face of Russian and Chinese opposition, to push through a motion that could allow stronger measures against Assad. Moscow fears this could lead to military action that could undermine its interests in Syria.

What began as demonstrations against Assad developed last year into armed rebellion, tipping the country towards a sectarian civil war, with thousands already killed across Syria.

Davutoglu said the jet was unarmed and had been on a solo mission to test domestic radar systems, but acknowledged it had briefly crossed Syrian airspace 15 minutes before it was attacked. There was no "secret" element to its mission.