U.N. inspectors have visited a Damascus suburb to meet victims of suspected chemical weapon attacks, after the Syrian government accepted international demands to grant access to the team.
The inspectors spent several hours in the southwestern suburb of Moadamiyeh on Monday, before returning to their hotel in the capital. Moadamiyeh is one of several rebel-held districts where the August 21 attacks took place.
The U.N. team met with doctors and survivors of the attacks at a makeshift hospital and took samples.
Syrian rebels and the government have blamed one another for the killings of hundreds of civilians in the incidents.
Western powers say they believe forces loyal to Syrian President Bashar al-Assad were responsible. Leaders of the United States, Britain and France have been discussing what action to take in response, raising the prospect of Western military intervention in Syria's two-year conflict.
The foreign minister of Russia, a key Assad ally, said Western powers "cannot produce any evidence" that the Syrian government committed the alleged chemical attacks.
Speaking Monday, Sergei Lavrov accused the West of "hysteria" and warned that any military action against Damascus would be a "gross violation of international law."
U.S. Defense Secretary Chuck Hagel said any action will be taken "in concert with the international community and within the framework of legal justification." He made the comment on a visit to Indonesia.
The highest concentration of casualties from last Wednesday's attacks was reported in the eastern Damascus suburb of Ghouta. It was not clear when the U.N. team would visit that location.
As the inspectors arrived in Moadamiyeh, snipers fired at one of their vehicles, damaging it and forcing the team to return to a government checkpoint before heading inside the rebel district. No one was hurt. The Syrian government and rebels accused one another of responsibility.
Earlier Monday, U.N. Secretary-General Ban Ki-moon said the success of the U.N. inspectors' mission could deter the future use of chemical weapons in Syria and elsewhere.
"All those in Syria have a stake in finding out the truth. The whole world should be concerned about any threat or use of chemical weapons, and that is why the world is watching Syria."
A senior Obama administration official said Sunday the U.N. team may not be able to accomplish much because the Syrian government prevented the inspectors from visiting the alleged attack sites for five days.
The official said the delay meant available evidence had been "significantly corrupted as a result of the regime's persistent shelling and other intentional actions."