A rebel military leader who was among the first to call openly for armed insurrection against President Bashar al-Assad was wounded by a bomb planted in his car in eastern Syria, anti-regime activists said Monday.

Col. Riad al-Asaad, leader of a now-sidelined rebel umbrella group known as the Free Syrian Army, had his right foot amputated following the blast late on Sunday, according to an activist in the town of Mayadeen where the attack took place.

The Britain-based Syrian Observatory for Human Rights also reported the attack, saying some said Asaad had been killed while others said he lost a leg.

A Free Syrian Army fighter takes cover in a building during clashes against the Syrian Army in Aleppo, Syria, Tuesday, Sept. 25, 2012. Manu Brabo/Associated Press (Manu Brabo/Associated Press)

Calls to Asaad's cellphone went unanswered, and one of his aides reached in Turkey said he had no details.

There was no immediate claim of responsibility for the attack.

Asaad, a former colonel in the Syrian air force who defected and fled to Turkey in 2011, became the head of the Free Syrian Army, a group of army defectors who were among the first to declare armed struggle the only way to topple the regime.

"They will soon discover that armed rebellion is the only way to break the Syrian regime," Asaad told The Associated Press in October 2011, soon after his group was formed.

At the time, most Syrian activists were inspired by the uprisings that had successfully toppled dictators in Tunisia and Egypt and thought popular protests would bring about the same result in Syria. But the Syrian government's vast, violent crackdown on opposition caused many to resort to arms.

70,000 killed since civil war began

Hundreds of independent rebel groups are fighting a civil war against Assad's forces across the country and many activists no longer bother to stage unarmed protests. The UN says more than 70,000 people have been killed since the first protests in March, 2011.

During that transition, Asaad, who spent most of his time in a refugee camp in Turkey, never managed to build effective links with most rebel groups or provide the support that would have made them recognize him as their leader. While most fighters in Syria refer to themselves as part of the "Free Army," those who say they follow Asaad are rare.

More recently, Asaad's group has been superseded by the Office of the Chiefs of Staff, which is associated with the opposition Syrian National Coalition and led by Gen. Salim Idris. That body, too, has failed to project widespread authority inside Syria, where most groups still cobble together their own funding and arms.

The Mayadeen activist said via Skype that a bomb planted in the seat of the car Asaad was riding in blew up as he toured the town.

The activist said rebels now control the town and most of the surrounding areas, although President Assad still has supporters, whom the activist blamed for the attack. He spoke on condition of anonymity out of concern for his safety.

Asaad was travelling with an aide and a local activist, Barakat al-Haweish, both of whom were slightly injured, the activist said. Asaad was taken to a local field hospital, where doctors amputated his right foot before transporting him to Turkey.

Also Monday, the opposition's exile political leadership, the Syrian National Coalition, said a delegation was heading to Doha, where the Gulf state of Qatar will host a two-day Arab League summit starting Tuesday.

Chief of Staff of the Free Syrian Army Gen. Salim Idris addresses the media after he discussed the situation in Syria with the leader of the Group of the Alliance of Liberals and Democrats for Europe . (Geert Vanden Wijngaert/Associated Press)

Foreign ministers of the League's member states decided Monday to grant Syria's seat in the body to the opposition. The Syria government's membership was suspended earlier in the uprising.

Heading the delegation is Mouaz al-Khatib, the Coalition said in a statement on its Facebook page. He is going despite having resigned his position as Coalition leader on Sunday, citing restriction on his work inside the group and frustration with the level of international aid for the opposition.

Khatib, a respected Muslim preacher before being chosen last year to head the Coalition, said in a post on his own Facebook page that he would address the summit "in the name of the Syrian people." He said the move had nothing to do with his resignation, "which will be discussed later."

The Coalition refused his resignation and has asked him to keep his job.

Also in the delegation is Ghassan Hitto, whom the coalition elected last week to head a planned interim government to govern rebel-held areas.

Mortar strikes hit Damascus

In Damascus, a series of mortar strikes near a downtown traffic circle on Monday killed two people and wounded several others, the government-run Ikhbariyeh TV station reported.

Umayyad Square, at the centre of a large intersection 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 dead and at least six wounded in the strikes, which it said hit near the Opera House.

It was unclear who was behind that attack as well, reflecting the often chaotic nature of Syria's two-year-old civil war pitting hundreds of independent rebel groups against the forces of Assad. The UN says more than 70,000 people have been killed since the conflict began with political protests in March, 2011.

Such sporadic strikes on Damascus have grown more common in recent weeks and often appear to target government buildings. Most cause only material damage, but spread fear in Damascus that the capital, which has so far managed to avoid the widespread clashes that have destroyed other cities, could soon face the same fate.

Damascus residents reported hearing intensive shelling on Monday, though it was hard to tell where it was coming from.