Amateur video posted on the Internet purports to show weapons inspectors in rebel-held Damascus collecting samples and photographing canisters.
U.N. chemical weapons experts investigated sites of last week's apparent poison gas attack in a rebel-held suburb of Syria's capital, after the inspectors themselves survived sniper fire that hit their convoy.
The investigators crossed the front-line from the centre of the capital, which remains under Assad's control, to inspect the Mouadamiya suburb, one of at least four neighbourhoods hit by poison gas last Wednesday (August 21) before dawn.
The U.N. said one vehicle in its convoy was crippled by shooting by "unidentified snipers", but mentioned no injuries.
A U.N. statement said one of the inspectors' cars had been disabled by bullets as they set out across the front line.
"The first vehicle of the Chemical Weapons Investigation Team was deliberately shot at multiple times by unidentified snipers in the buffer zone area," it said. "It has to be stressed again that all sides need to extend their co-operation so that the team can safely carry out their important work."
Syrian state television blamed rebel "terrorists" for the shooting. The opposition blamed it on pro-Assad militiamen.
Presented by Adam Justice