DAMASCUS: A car bomb killed 13 people in central Damascus on Sunday as President Bashar al-Assad told an international mediator seeking a truce in Syria's civil war that the key to any political solution was to stop arming rebels.

The bomb exploded outside a police station in the mainly Christian central Bab Touma district of the capital while Assad held talks with United Nations-Arab League envoy Lakhdar Brahimi, who is pushing for a temporary ceasefire to mark the Islamic festival of Eid al-Adha.

State news agency SANA said the president said Syria supported "any sincere effort to find a political solution to the crisis, based on respect for Syrian sovereignty and rejecting foreign intervention."

Any proposal "must be centred around the principle of halting the terrorism and ... commitment by the countries involved in supporting, arming and harbouring the terrorists in Syria to stop these actions", SANA quoted Assad as saying.

Syrian authorities blame neighbouring Turkey in particular for the bloodshed because it has sheltered mainly Sunni Muslim rebels fighting to overthrow Assad, from Syria's Alawite minority which is an offshoot of Shi'ite Islam. Gulf Sunni powers Saudi Arabia and Qatar also support arming the rebels.

Syria's conflict, which started with peaceful protests for reform, has escalated into a civil war marked by heavy use of artillery and air power by Assad's forces and regular bombings against symbols of his authority in Syria's main cities.

The Interior Ministry said the Bab Touma bomb, on the edge of the old city of Damascus, killed 13 people. Security forces cut off access to the area. Television pictures showed shattered glass on the road and several burnt out cars.

Speaking after his meeting with Assad, Brahimi gave few details of the talks but reiterated his call for a pause in the violence, which activists say has killed more than 30,000 people since the uprising against Assad erupted in March last year.

"Everyone can start this (ceasefire) when they want, today or tomorrow for example, for the period of the Eid and beyond," he told reporters at a Damascus hotel. Eid al-Adha begins at dusk on Thursday, lasting for three or four days.

Brahimi said he had contacted opposition figures inside and outside Syria, including rebel fighters, as well as officials in neighbouring countries, some of which support the insurgency.

"They answered that they would respond positively to a (ceasefire) initiative from the government," he said. "We hope this Eid in Syria will be calm, even if it is not a happy Eid."

He added: "If we do find that this calm continued through the Eid, we will try to build on it. If that does not happen, we will try nevertheless and work to open the path to hope for the Syrian people."

Turkey has called for all sides to observe Brahimi's truce. Iran, one of Assad's major backers, has also supported the call but said the main problem in Syria was foreign interference, such as arming the rebels.

The United States, which has been a vocal critic of Assad but has little apparent influence on the ground, threw its weight behind the ceasefire call on Friday.

A previous ceasefire in April collapsed after just a few days, with each side blaming the other. Mediator Kofi Annan resigned his post in frustration a few months later.

The violence has spread across Syria's frontiers. Assad's forces exchanged cross-border artillery fire with Turkey several times this month and on Friday a huge car bomb in Beirut killed a top intelligence official whose investigations had implicated Syria in trying to stoke violence on Lebanese soil.

Syria's Information Minister Omran Zoabi told reporters on Friday: "We condemn this terrorist explosion and all these explosions wherever they happen. Nothing justifies them."