BEIRUT, Lebanon - Turkey announced Friday that Syrian forces had shot down a Turkish warplane with two crew members over the Mediterranean, a potentially ominous turn in relations already frayed because of Turkey's support for Syrian rebels fighting to overthrow President Bashar Assad.
The Syrians later acknowledged their antiaircraft gunners had downed the plane, contending it had violated Syrian airspace.
Turkey's announcement, from the office of Prime Minister Recep Tayyip Erdogan, came after an emergency security meeting by Turkish officials in Ankara over the fate of the plane, which had been reported missing hours earlier amid conflicting reports over whether it had crashed or had been downed intentionally.
The measured wording of the announcement suggested that Turkey had not yet concluded that the Syrian action was provocative, and it acknowledged that Syrian rescue teams were cooperating in trying to locate the aircraft and crew. But the statement also left open the possibility that Turkey, a NATO member, would respond militarily.
"As the result of the data provided by our related institutions and the research jointly conducted with Syria, it was understood that our plane has been downed by Syria," said the statement from Erdogan's office. "Turkey, after the incident is fully enlightened, will lay forward its attitude and take necessary steps."
The plane, identified by Turkish and Western news agencies as a U.S.-made F-4 Phantom, went down near the southern coast of Hatay province in Turkey, which borders Latakia province in Syria.
The new rupture in Turkish-Syrian relations came as reports of a possible new mass killing emerged Friday in Syria's northern Aleppo province.
Opposition activists said those killings, in the village of Daret Azzeh, were the outcome of a military skirmish in which soldiers of the Free Syrian Army, the main armed rebel force, carried out a surprise attack on a group that included suspected members of the shabiha, the feared pro-government militia. At least 25 men were shot to death.
The official Syrian Arab News Agency's account of the Daret Azzeh killings attributed them to armed terrorist gangs, the standard government description for all opposition forces.
At least 56 people were killed elsewhere in clashes and protests around Syria, opposition accounts said.