The Turkish army have announced it lost contact with a military plane near Syria, triggering an emergency meeting with Turkey's top military, intelligence and government officials.
Turkey's military command said in a brief statement that it lost radar and radio contact with one of its aircraft on the Mediterranean in the southwest of the Hatay province bordering Syria.
The plane took off from Malatya airbase in the southeast at 0730 GMT and lost communication with the base at 0858 GMT, the online statement said.
The incident prompted an emergency security meeting led by Prime Minister Recep Tayyip Erdogan, who was expected to return from Brazil later in the day, said Anatolia news agency.
The meeting will also include the heads of the military and intelligence, as well as interior, foreign and defence ministers, it added.
Malatya governor Ulvi Saran told the Anatolia news agency that the aircraft was a F-4 fighter jet with two pilots onboard, without elaborating further.
"We have no information right now about the fate of the plane. We are following the developments," he said.
Mr Erdogan was meanwhile quoted by local media as saying that the two pilots are alive.
NTV private news channel reported citing unnamed military sources that the plane crashed in Syrian territorial waters, but there was no violation of the Syrian border. But the claims were not confirmed by Turkish officials.
US Defence Secretary Leon Panetta has defended the Obama administration's decision not to arm the Syrian opposition.
He said the country risked being pushed into an all-out civil war if efforts to secure a smooth political transition fail.
"We made a decision not to provide lethal assistance at this point. I know others have made their own decisions," Mr Panetta said in an interview.
Meanwhile, the number of people needing humanitarian assistance in Syria has risen to 1.5 million from the previous estimate of 1m, the United Nations Office for the Coordination of Humanitarian Affairs has said.
The UN World Food Programme had distributed food to 461,000 Syrians by mid-June and aims to increase that number to 850,000 in July, officials said.