BEIRUT Armoured vehicles headed towards southern districts of Damascus after rebels battled government forces into the early hours of Monday, in what residents said was the heaviest fighting in the capital in a 17-month revolt against President Bashar al-Assad.
Columns of armoured vehicles were seen on the main road leading to the Tadamon district, a Damascus activist said.
At least five people were killed and dozens more wounded in Sunday's fighting but residents said people were returning to work and shops were starting to open in Damascus on Monday morning after the fierce exchanges died down.
The spread of fighting to the capital came as U.N. peace mediator Kofi Annan planned a two-day visit to Moscow in which he will meet Russian President Vladimir Putin who has resisted Western calls to increase pressure on Assad.
Activist Samir al-Shami, who spoke to Reuters by Skype from Damascus, said Sunday's fighting in Tadamon came after sustained battles began at nightfall the previous day in the nearby Hajar al-Aswad district.
"There is the sound of heavy gunfire. And there is smoke rising from the area. There are already some wounded and residents are trying to flee the area," he said, using Skype to show live video images of smoke visible over the skyline.
"There are also armoured vehicles heading towards the southern part of the neighbourhood," he said.
Another activist reached by Skype said the fighting later spread to al-Lawan, a neighbourhood on the southwestern outskirts of the capital.
A third activist, who also asked not to be identified, said: "We've been expecting things to worsen in Damascus after the army crushed the rebellions in some of the suburbs, like Douma outside the capital.
"There were thousands of fighters in some of those suburbs. Some of them were killed but a lot of them fled and they've been heading to the capital itself," the activist said.
Some residents said the fighting eased slightly as the night wore and said there had been a number of protests in support of the opposition in the poorer neighbourhoods of Damascus.
One local, who gave his name as Tarek, said residents set tyres ablaze to distract the security forces and relieve pressure on the fighters in Tadamon.
The government restricts access to the country by independent media, making verification of events difficult.
Annan travels to Moscow days after opposition reports of a new massacre prompted a fresh wave of denunciations in the West where there are hopes Putin might ease his support for Assad.
But Moscow has shown no public sign of wavering in its backing for its last major Arab ally, a customer for its arms and host to a Russian naval support base.
Along with China, Russia has blocked tougher U.N. Security Council action and the West has shown no appetite for the kind of intervention it undertook last year when NATO helped topple Libya's Muammar Gaddafi.
Annan said on Friday he was "shocked and appalled" at the government for breaking a promise not to use heavy weapons in populated areas, and that it was confirmed that helicopters and artillery had fired on the village of Tremseh.
The Syrian government said it killed several dozen enemy fighters in Tremseh but denied carrying out a massacre or that its forces used heavy weapons.
Syrian Foreign Ministry spokesman Jihad Makdissi criticised Annan for jumping to conclusions by accepting opposition reports of the incident last week.
"What happened was not a massacre ... what happened was a military operation," Makdissi told a news conference in Damascus. "Government forces did not use planes, or helicopters, or tanks or artillery."
U.N. observers returned to the village on Sunday to gather more evidence at the site after finding signs that artillery was used but inconclusive evidence of the scale of the killing.
Opposition footage of the incident on the Internet has shown bloody corpses of men, but not women or children, making it difficult to determine whether those killed were fighters.
Sander van Hoorn, a Dutch journalist who reached Tremseh, said by Twitter that he had counted 30 graves in the town and had seen clear evidence of shelling, including of a school used as a shelter by refugees.
He said the evidence on the ground clearly contradicted the government's assertion that no heavy weapons were used. But he also said he had not yet seen signs of a massacre like one that took place in the city of Houla in May, when the United Nations says 34 women and 49 children were among 108 people killed. (Writing and additional reporting by Mariam Karouny; editing by Samia Nakhoul and Jon Boyle)