Colonel Riad al Asaad, founder of the rebel Free Syrian Army (FSA), lost a leg in an explosion in Syria overnight and is in Turkey for treatment, Turkish officials said.

Col Asaad, who established the FSA in 2011 to fight for the overthrow of President Bashar al Assad, was one of the first senior officers to defect from the Syrian military.

The Turkish official, who asked not to be identified, said Col Asaad's wounds were not life-threatening.

Syrian opposition sources said Col Asaad had been hit by a car bomb in the city of al Mayadin, south of Deir al Zor in eastern Syria.

These accounts could not immediately be confirmed.

"The attempt to assassinate Colonel Riad al Asaad in Deir al Zor is part of an attempt to assassinate the free leaders of Syria," said Moaz al Khatib, who resigned on Sunday as the head of the opposition Syrian National Coalition.

Col Asaad was excluded from a western-backed command of the FSA formed last year.

Since his defection he has mostly lived with his family in a camp in Turkey along the Syrian border.

Various Syrian rebel factions fight under the umbrella of the FSA, which has struggled to find regular weapons supplies and build a disciplined command and control structure.

Some prominent Islamist militant groups, including the powerful al Qaeda-linked Nusra Front, are not part of the FSA.

Meanwhile, a series of mortar strikes near a central Damascus round-about killed one person and wounded several others, the government-run Ikhbariyeh television station reported.

Umayyad Square, at the centre of a large inter-section west of downtown, sits near the government TV headquarters, the Sheraton hotel and a number of faculties of the University of Damascus.

Syria's state news agency reported no deaths and at least six injured in the strikes, which it said hit near the Opera House.