Participants of a UN briefing in Geneva said the evidence of alleged chemical weapons attack in Syria was fake, Russian Foreign Ministry said Tuesday.

Participants of the Monday briefing in Geneva noted that video footage and photo images of the chemical attack near Damascus have been cooked in advance, the ministry said in a statement published on its website.

International experts, Syrian representatives and a Russian TV reporter used to work in Syria attended the briefing.

"Numerous witnesses said unanimously that chemical weapons at East Guta was used by the rebels," the ministry added.

They also said that "the US leadership must be accounted for illegal threats to use force against Syria," said the statement.

Also on Tuesday, Alexei Borodavkin, Russia's UN Permanent Representative in Geneva, condemned the use of chemical weapons in Syria which he called "a provocation."

The diplomat, who participated in the 24th session of the UN Human Rights Council in Geneva on Monday, called for a thorough probe by UN experts following the alleged chemical weapons use in Syria.

He reminded that Russia recently offered Damascus to put Syrian chemical arsenals under international control, to destroy them subsequently and to join Organization for Prohibition of Chemical Weapons (OPCW).

Still, there are worrisome signals about the possibility of outside intervention into Syrian conflict without US consent keep coming, the Russian diplomat said, adding such an intervention would constitute a gross violation of international law and will manifest an act of aggression.