A Turkish military operation to rescue 40 soldiers guarding a tomb in Syria surrounded by militants of the so-called ’Islamic State of Iraq and the Levant’ (ISIL) takfiri group was launched to counter a possible attack on them.

A Turkish military operation to rescue 40 soldiers guarding a tomb in Syria surrounded by militants of the so-called 'Islamic State of Iraq and the Levant' (ISIL) takfiri group was launched to counter a possible attack on them, presidential spokesman Ibrahim Kalin said on Monday.

The action, which involved tanks, drones and reconnaissance planes as well as several hundred ground troops, was the first of its kind by Turkish troops into Syria since the start of the civil war there nearly four years ago.

"With this operation, our government has removed the risk of a possible attack on the tomb and the military post, and of endangering the lives of our soldiers," Kalin told a news conference in Ankara. 

The Syrian government described the operation as an act of "flagrant aggression", a response dismissed by Kalin, who - according to Reuters - said the Syrian authorities had lost all legitimacy.

He also said Turkey was working intensively with the British authorities to trace three London schoolgirls who travelled to Turkey last week and are believed to be making their way to Syria.

Thousands of foreigners from more than 80 nations including Britain, other parts of Europe, China and the United States have already joined the ranks of ISIL and other radical groups in Syria and Iraq, many crossing through Turkey.

Syria was hit by a violent unrest since mid-March 2011, where the western media reports accuse countries, mainly the USA, Turkey and Saudi Arabia of orchestrating the civil conflict in the country and providing terrorist groups with money, weapons and trained mercenaries.