A taxi rigged with explosives blew up near a police station in the Syrian capital Sunday, killing at least 13 people as the UN peace envoy was visiting Damascus to push his call for a ceasefire in talks with President Bashar Assad.

Syria's SANA state news agency said 29 people were also wounded in the blast in the Bab Touma neighborhood, a popular shopping district largely inhabited by Syria's Christian minority.

Once largely immune to the violence that has swept over Syria since the anti-Assad revolt began in March 2011, Damascus has become a frequent target of bombings in recent months. There was no immediate claim of responsibility for Sunday's blast, but Islamist groups fighting alongside the rebels have claimed to be behind bomb attacks against security targets in the capital.

Two Syrian officials speaking from the scene said the taxi blew up 50 metres from Bab Touma's main police station. The officials insisted on anonymity because they were not allowed to brief the media.

An Associated Press reporter at the site of the blast said blood stained the street and sidewalks, shards of glass littered the pavement from shattered shop windows and the charred hulks of at least four cars littered the street.

Vegetable vendor Mohammad Hanbali, 27, said several people wounded in the blast were lying on the street when he rushed to help.

"It's a cowardly act, carried out by terrorists," said Hanbali, who was hit by a piece of shrapnel in the left leg.

SANA put the death toll at 13, while the anti-regime Syrian Observatory for Human Rights said at least 10 people were killed in the blast.

No commitment to ceasefire from Syrian opposition

In another part of capital, UN and Arab League envoy Lakhdar Brahimi met with Assad as part of his push for a cease-fire between rebels and government forces for the four-day Muslim holiday of Eid al-Adha, which begins Oct. 26.

Brahimi told reporters following a closed-door meeting that he met earlier with Syrian opposition groups inside and outside the country to discuss his truce plan. He said he received "promises" but not a "commitment" from them to honour the ceasefire.

He noted that he "found an overwhelming response" from Assad's opponents to his cease-fire plan and that "all of them have said that it's a good idea which they support."

He declined to reveal Assad's response to his plan, viewed as a preliminary step toward a larger deal.

But SANA said Assad assured Brahimi that he supported his effort, but did not say whether he committed to a truce.

"The president said he is open to any sincere effort to find a political solution to the crisis on the basis of respecting the Syrian sovereignty and rejecting foreign interference," SANA said.

It said Assad also stressed that a political solution must be "based on the principle of halting terrorism, a commitment from the countries involved in supporting, arming and harboring terrorists in Syria to stop doing such acts." Syrian authorities blame the anti-government uprising that began in March last year on a foreign conspiracy and accuse Saudi Arabia and Qatar, along with the U.S, other Western countries and Turkey, of funding, training and arming the rebels, whom they describe as "terrorists."

For months, Turkey served as headquarters for the leaders of the ragtag Free Syrian Army before the rebel group shifted its command to Syria. Turkey also hosts many meetings of the Syrian National Council opposition group. Relations between Turkey and Syria, once close, have been deteriorating since the crisis began last year and Ankara became one of President Bashar Assad's harshest critics.

Brahimi said he was "hopeful that the eid in Syria will be calm if not happy." He said that he will return to Syria after the holiday. "If we find that this calm is actually achieved during the Eid and continued, we will try to build on it," he added.

"The Syrian people expect more than a truce for a few days and it is their right, but all we can promise is that we will work hard to achieve their aspirations," he said.

Elsewhere, in the northern city of Aleppo, a suicide bomber detonated his explosive-laden car in front of the French-Syrian Hospital at al-Zohour Street, causing material damage, but no casualties, SANA said. It said the blast wounded several passers-by, but did not disclose their number.

Anti-regime activists say more than 33,000 people have been killed since the anti-Assad revolt started.