BEIRUT - Syrian government forces pressed their offensive in eastern Damascus on Thursday, bombing rebel-held suburbs where the opposition said the regime had killed more than 100 people the day before in a chemical weapons attack.
The government has denied allegations it used chemical weapons in artillery barrages on the area known as eastern Ghouta on Wednesday as "absolutely baseless."
The U.S., Britain and France have demanded that a team of U.N. experts already in Syria be granted immediate access to the site.
Syrian opposition figures and activists have reported death tolls from Wednesday's attack ranging from 136 to 1,300. But even the most conservative tally would make it the deadliest alleged chemical attack in Syria's civil war.
The Britain-based Syrian Observatory for Human Rights said it had no word on casualties in the Thursday morning bombing. It said warplanes conducted several air raids on eastern and western suburbs of Damascus, including three that took place within five minutes.
The Local Coordination Committees, another activist group, also reported several air raids on the suburbs, and added that President Bashar Assad's forces were shelling eastern Ghouta from the Qasioun mountain overlooking Damascus.
Wednesday's alleged chemical attack was said to have killed scores of children, seen in amateur videos as small, lifeless bodies, wrapped in white cloths, their pale skin unmarked by any wounds.
Images of dead children lying shoulder to shoulder in rooms and of others being treated for breathing problems brought worldwide condemnation and shock.
Mohammed Abdullah, an activist in the suburb of Saqba, told The Associated Press via Skype on Thursday that most of the dead were buried hours after the attack in collective graves in different areas in eastern Ghouta. The burials took place quickly for fear the bodies might decompose in the heat, he said.
Relatives identified some of the dead before burial. Unidentified victims were photographed and their graves tagged with a number in case their loved ones come to collect their bodies in the future, Abdullah said.
"Most of the dead were buried in mass graves," he said.
In a statement calling the reports "deeply disturbing," UNICEF said: "This terrible conflict has gone on far too long and children have suffered more than enough.
"Children must be protected, and those who fail to protect them will be held accountable," it said.
From New York, the U.N. Security Council called for "a thorough, impartial and prompt investigation."