BEIRUT // Rebels fought regime forces at the gates of Aleppo's ancient Old City yesterday in a battle for control of Syria's commercial hub.
Residents and opposition activists said the army was bombarding several quarters of Aleppo with artillery and mortars as helicopter gunships flew overhead.
Troops and rebels clashed in Bab Al Hadeed and Bab Al Nasr, two of several gates to the walled old quarter, a United Nations World Heritage site.
Majed Al Nour, an opposition activist, said the rebels had "moved to try to liberate" the city centre after taking over several neighbourhoods.
Mustapha Abdullah, commander of a rebel unit called the Martyrs of Aleppo, said a lack of ammunition was becoming a problem. "Rebels are coming from the countryside but they are running out of ammunition and arms," he said.
Forces loyal to Bashar Al Assad were shelling the countryside north of Aleppo to disrupt rebel advances, he said. "We are attacking in small groups in hit-and-run operations."
As the battle for Syria's second city intensified, there was confusion over the opposition Syrian National Council's view on who ought to lead a transitional government if the regime in Damascus should fall.
Hours after the SNC said it would accept a regime figure provided Mr Al Assad stepped down as president, the group said only "a national consensus figure from the opposition" would be charged with leading the country in a transition phase, and such a figure would "not be part of the regime".
The regime itself also backpedalled on its admission that it held stockpiles of chemical and biological weapons, and its threat to use them if it were attacked by a foreign power.
Jihad Makdissi, a foreign ministry spokesman, said on Monday that no chemical or biological weapons would be used on the domestic uprising, but "all of these types of weapons are in storage and under security and the direct supervision of the Syrian armed forces and will never be used unless Syria is exposed to external aggression".
The Syrian information minister Omran Al Zoubi said yesterday that Mr Makdissi's comments had been misconstrued and taken out of context.
When Mr Makdissi said Syria would not use non-conventional weapons against its own people, it did not mean the country was in possession of such arms, Mr Al Zoubi said.
Syria's stockpile of non-conventional weapons is believed to be among the largest in the region and to include nerve agents and mustard gas.
The US Secretary of State Hillary Clinton insisted yesterday there was still time for Mr Al Assad to hand over power.
"We do believe that it is not too late for the Assad regime to commence with planning for a transition to find a way that ends the violence," she said, and matters were "accelerating inside Syria".
Recep Tayyip Erdogan, Turkey's prime minister, said he believed the uprising against the Assad regime was "closer than ever to victory". Nabil Elaraby, the head of the Arab League, said there was no more talk of political reform in Syria, but of a "transfer of power".
However, a senior member of Iran's Revolutionary Guards warned against foreign intervention in the conflict, specifically cautioning against Arab involvement.
General Masoud Jazayeri said the Assad regime had allies in the region who would "strike out", particularly at the "hated Arabs", without naming any countries.
The Local Coordination Committees said yesterday that about 10 people, including children, were killed when the building where they had sought shelter from government shelling in the town of Herak in Deraa was hit. The group said the shelter had been targeted.
Video footage posted online showed the bloodied bodies of six young children said to have been killed in the bombing.
"The world is watching. Where are the Arabs and Muslims when these children are killed during Ramadan?" a voiceover says.
These reports could not be verified.
The LCC said at least 91 people were killed across Syria yesterday, including 20 in Aleppo. Opposition activists also said between 10 and 15 prisoners were killed in a jail close to Aleppo after Syrian forces suppressed a riot.
Violence also continued to rock the Syrian capital, with explosions in the central neighbourhood of Barzeh, which was raided by government troops.
* With additional reporting by Agence France-Presse, Associated Press and Reuters