LONDON -- As fighting flared in northern areas of the Syrian capital, Damascus, after fierce clashes to the east, Prime Minister David Cameron of Britain on Friday echoed the Obama administration's cautious assessment of the use of chemical munitions in Syria, saying there was limited but growing evidence that such weapons had been used, probably by government forces.
There was no indication that Mr. Cameron, speaking on a BBC television show, was referring to the latest fighting around Damascus. Syrian state media claimed on Thursday that government forces had overrun a strategic, rebel-held town controlling a key insurgent supply corridor to the east of the capital.
On Friday, antigovernment activists posted video footage said to show heavy clashes between government forces and rebels in the Barzeh area of northern Damascus, with gray and black smoke rising from battered high-rises into the early morning sky. The provenance of video could not be independently verified.
While the fighting swirled on the ground -- with explosions clearly audible from the center of Damascus on Friday -- much Western attention has been focused on whether chemical weapons have been used to the extent that they might trigger foreign military intervention, a possibility that Mr. Cameron sought to rule out on Friday.
The British government, like Washington, is concerned about avoiding a repetition of the events that led to the 2003 invasion of Iraq when the presence of unconventional weapons, cited as justification for military action, had never been corroborated.
The White House said on Thursday that the nation's intelligence agencies had assessed "with varying degrees of confidence" that the government of the Syrian president, Bashar al-Assad, had used sarin, a chemical agent, on a small scale.
But it said more conclusive evidence was needed before Mr. Obama would take action, referring obliquely to the Bush administration's use of faulty intelligence in the march to war in Iraq and the ramifications of any decision to enter another conflict in the Middle East.
On Friday, Mr. Cameron said that while evidence was limited, "there's growing evidence that we have seen, too, of the use of chemical weapons, probably by the regime. It is extremely serious, this is a war crime, and we should take it very seriously."
Mr. Cameron said British authorities were trying to avoid "rushing into print" news about the use of chemical weapons.
"But this is extremely serious, and I think what President Obama said was absolutely right -- that this should form for the international community a red line for us to do more," he said.
He repeated that Britain had no appetite to intervene militarily, as it did in Iraq and Afghanistan.
"I don't want to see that, and I don't think that is likely to happen," he said. "But I think we can step up the pressure on the regime, work with our partners, work with the opposition in order to bring about the right outcome. But we need to go on gathering this evidence and also to send a very clear warning to the Syrian regime about these appalling actions."
He was speaking a day after Syria's state news media said government forces had "restored complete control" in a strategic, bitterly contested town east of Damascus, offering new claims -- disputed by rebel fighters on the ground -- that loyalist troops were reversing the flow of battle in some areas, severing a crucial insurgent supply line on the approaches to the capital.
SANA, the official news agency, said soldiers fighting on the side of Mr. Assad had overwhelmed the opposition in the town, Otaiba, and had "discovered a number of tunnels which were used by terrorists to move and transfer weapons and ammunition."
Terrorist is the word used by Mr. Assad to describe armed opponents, backed by the West and many Arab states, seeking his overthrow in a revolt that is now more than two years old.
Rebel fighters on the ground said on Thursday that despite the official claims, the insurgents were still holding on to some parts of Otaiba.
Alan Cowell reported from London, and Hwaida Saad from Beirut, Lebanon.
This article originally appeared in The New York Times.