BEIRUT – Turkey vowed to take “necessary steps” after concluding that Syria had shot down a Turkish fighter jet along the Syrian border Friday.

In a statement issued early today after an emergency security meeting summoned by Prime Minister Recep Tayyip Erdogan, the Turkish government said that an F-4 fighter jet that disappeared over the southern Turkish province of Hatay had been brought down by Syria. The statement said Turkey “will make its final position known once the evidence is uncovered and will determinedly take necessary steps.”

The Turkish military said Friday that it lost contact with the plane shortly before noon. A hunt was under way in the eastern Mediterranean for the jet’s two missing pilots, and Syrian vessels were helping Turkish ships and helicopters with the search, Erdogan said.

The episode underscored the region’s jittery mood as the Syrian revolt degenerates into an armed conflict that many fear will spill beyond its borders and draw in its neighbors. Compounding the tensions, Turkey has emerged as the main conduit for the new supplies of weaponry that are now flowing to Syrian rebels with funds from Saudi Arabia and Qatar and facilitated in part by the United States.

The government’s statement capped a day of unconfirmed reports that Syria was responsible for bringing down the plane and had subsequently apologized.

Al-Manar, the TV network run by Lebanon’s pro-Syrian Hezbollah movement, quoted Syrian “security sources” in Damascus as saying it had been shot down, and Turkey’s state news agency Anatolia quoted Erdogan as saying that Syria had offered an apology. But Erdogan told reporters he could not confirm that Syria had apologized.

Nearly 30,000 Syrian refugees have flooded into southern Turkey over the past year, and the leadership of the rebel Free Syrian Army is being housed at one of the refugee camps.

Across the border in the Syrian provinces of Idlib and Latakia, the rebels have been waging pitched battles with the Syrian army as it seeks to recover territory that had fallen out of government control.

The disappearance of the Turkish plane came a day after a Syrian pilot flew his MiG-21 fighter jet to Jordan and requested political asylum, in the first such defection since the uprising began. The defection was a major embarrassment for Syrian President Bashar al-Assad’s government and is likely to have led to increased vigilance around Syria’s borders in case other pilots try to flee.

Meanwhile, violence continued in Syria on Friday, with the opposition Local Coordination Committees reporting the deaths of 55 people nationwide. Among them were at least eight people shot dead while staging an anti-government protest in the Salaheddine neighborhood of the northern city of Aleppo.

In addition, the Britain-based Syrian Observatory for Human Rights reported the discovery of the bodies of 25 men in one of the rural areas of Aleppo province that are falling out of government control. They had apparently been executed in a mass killing by rebel forces.