A Turkish fighter jet shot down a Syrian military helicopter on Monday after it entered Turkish airspace and ignored repeated warnings to leave, an official has said.
The helicopter strayed 2km into Turkish airspace, but crashed inside Syria after being hit by missiles fired from the jet, according to Turkey's Deputy Prime Minister, Bulent Arinc.
Arinc said he did not have any information on the fate of the Syrian pilots, but Rami Abdul-Rahman, director of the Syrian Observatory for Human Rights, said rebel fighters captured one of the pilots, while the fate of the other one was unclear.
Turkey scrambled two F-16 jets along the border between its southern Hatay province and Syria after warning that the Mi-17 helicopter was approaching Turkish airspace, the military said in a statement.
It came down in a ball of flames inside Syrian territory after being hit, amateur video footage showed.
Syria's army said that Turkey had been "hasty" in shooting down its helicopter and accused Prime Minister Tayyip Erdogan's government of trying to escalate tensions along the border.
"The hasty response from the Turkish side, especially as the aircraft was on its way back and was not charged with any combat missions, is proof of the true intentions of Erdogan's government toward Syria to increase tensions and escalate the situation on the border between the two countries," Syria's armed forces said in a statement reported by the state news agency SANA.
The incident is bound to ramp up tension on an already volatile border.
Turkey has been at odds with the Syrian government since early in the country's civil war and has backed the Syrian rebels, while advocating international intervention in the conflict.
Al Jazeera's Anita McNaught, reporting from near the Turkish-Syrian border in Atakya, said that Turkey changed its rules of engagement in June last year after a Turkish jet was allegedly shot down by Syrian air defences, declaring any Syrian "military instrument" on the Turkish border would be treated as a "military threat".
The Turkish Foreign Minister, Ahmet Davutoglu, speaking in Paris after meeting US Secretary of State John Kerry, British Foreign Secretary William Hague and their French counterpart Laurent Fabius, said Monday's encounter should send a message.
"Nobody will dare to violate Turkey's borders in any way again," he said. "The necessary measures have been taken."
He said details of the incident would be provided to UN Secretary-General Ban Ki-moon and the UN Security Council and fellow members of the NATO military alliance.
Turkey has bolstered its defences and deployed additional troops on its southeastern border in recent weeks, with convoys of military vehicles ferrying equipment and personnel and additional short-range air defences set up.
Its armed forces have frequently responded in kind to stray gunfire and mortar rounds hitting its territory and it is hosting six NATO Patriot missile batteries meant to defend it against any attacks from Syria.