MOSCOW: Russia is totally unconvinced by evidence presented by the United States and its allies of an alleged chemical attack outside Damascus that the West says was perpetrated by the Syrian regime, Foreign Minister Sergei Lavrov said Monday.

Moscow vehemently opposes US-led plans for military action against the regime of Bashar al-Assad in response to the alleged attack, even though the timetable has now been put back by President Barack Obama's decision to put it to Congress.

“What we were shown before and most recently by our American partners as well as the British and the French absolutely does not convince us,” Lavrov said at a university lecture in Moscow.

He added there were “many doubts” about images of the alleged attack posted on the Internet. President Vladimir Putin said over the weekend it would have been “utter nonsense” for the regime to launch such an attack when it has the military ascendancy.

Lavrov said Russia had been shown some evidence by the West but expressed scepticism over its validity, saying “there was nothing concrete, without geographic coordinates or names.”He accused the West of concealing comments by “many experts” who have expressed “serious doubts” about the validity of the video footage of the attack posted on the Internet.

“If we are going to state that these are pictures of the use of chemical arms and of the effects on the victims then there is a mass of disparities and absurdities,” Lavrov said.

“There are very many doubts,” he said. “There are no facts, just talk that 'we probably know this',” he added.

“And when you ask for more detailed evidence, they say that it is all secret and they cannot show you. Thus, there are no such facts for the purposes of international cooperation,” he added.

The dispute between the West and Russia over Syria is expected to be at the centre of the G20 summit which is to be hosted by Putin later this week in Saint Petersburg.