A Turkish fighter jet crashed into the waters off Syria on Friday, triggering fears of a confrontation between Nato and the Assad regime amid allegations that it had been shot down.

Recep Tayyip Erdogan, Turkey's prime minister, summoned his military and intelligence chief on Friday night after the Turkish Air Force lost radio and radar contact with one of its F-4 Phantom fighters during a mission off the Syrian coast.

Officials in Turkey and Syria would not be drawn publicly on the aircraft's fate. But residents in the Syrian city of Latakia, on the Mediterranean coast, claimed to have witnessed an unidentified plane being shot down at the roughly the same time the fighter vanished from radar scenes.

Two Lebanese television stations with close links to government of President Bashar al-Assad also quoted sources in Damascus as saying that it had been shot down by Syrian air defences.

They claimed the aircraft had entered Syrian air space, although Turkish military officials suggested it was over international waters.

In what would amount to an admission of guilt by the Assad regime, Turkish newspapers claimed that Mr Erdogan had received an apology from Syria.

"Syria immediately offered a very serious apology for the incident and admitted it was a mistake," The Habeturk newspaper quoted the prime minister as telling reporters on board a plane taking him back to Turkey from Brazil.

However, after he landed on Friday night, Mr Erdogan appeared to backtrack, saying he could not clarify the exact circumstances in which the plane came down, indicating that he needed to receive a more detailed briefing from senior military staff. He also said he had "no firm information" on a Syrian apology.

While the exact circumstances surrounding the aircraft's disappearance remained far from clear, any indication that it was brought down by Syrian fire could have major international repercussions.

As a member of Nato since 1952, Turkey could call on the alliance to support and perhaps even participate in any response it chooses to make.

It would almost certainly invoke Chapter IV of the Nato treaty, which allows a member to convene an emergency summit of the whole alliance if "the territorial integrity, political independence or security of any of the parties is threatened".

Turkey reportedly came close to invoking Chapter IV in April after Syrian forces opened fire into its territory, wounding two Turkish nationals and two Syrians at a refugee camp close to the border. It was persuaded not to by the United States.

An accurate picture of what exactly happened could become clearer after Turkish officials were quoted as saying that both pilots were rescued from the Mediterranean after they safely ditched from the stricken aircraft.

Turkey has been at the forefront of regional efforts to oust Mr Assad and has given sanctuary to rebels seeking his overthrow. With thousands of refugees pouring across its borders, it also led calls to impose a buffer zone inside Syrian territory but was rebuffed by Western powers.

Instead, Turkey has become a key conduit for the passage of Saudi and Qatari weapons to the Syrian rebels.

Officials in Ankara have expressed unease that this policy would leave the country vulnerable to Syrian retaliation and some will see yesterday's incident as evidence that their fears have been realised.

The United States gave Turkey strong assurances that it would not leave the country "hung out to dry" should it experience a backlash from Syria, a Western official in Washington told The Daily Telegraph last week.

The Obama administration could now come under strong pressure to deliver on its pledge, despite a deep reluctance in the West to become involved in any military action in Syria.

Turkey is unlikely, however, to be able to invoke Chapter V of the Nato treaty, which determines that an attack on one member should be viewed as an attack on all, because the clause only refers to hostile action taken on European or North American soil.

The incident came as the Syrian government accused its rebel foes of carrying out a "massacre" of Mr Assad's supporters after the emergence of grisly video footage showing more than a dozen bloodied and mutilated corpses.

A pro-opposition human rights group confirmed that rebels were behind the killings, but said that the victims were members of the pro-Assad Shabiha, the feared Alawite militia accused of murdering hundreds of Sunni civilians.

Although the rebels have been accused of atrocities in the past, the latest killings will raise fears that Syria is swiftly becoming locked into a unbreakable cycle of revenge killings and sectarian hatred.

Meanwhile, in a sign that the regime was losing control over its former strongholds, government troops killed at least ten people in Aleppo, Syria's largest city, after opening fire on a demonstrators with heavy machine guns, according to opposition activists.----

Source: http://www.telegraph.co.uk/news/worldnews/middleeast/syria/9350341/Downed-Turkish-jet-prompts-fears-of-Syrian-confrontation.html

UN Kofi Annan's declaration: