Russian Foreign Minister Sergei Lavrov today denied that Moscow was interfering with evidence of a suspected chemical weapons attack in Syria after Britain said international inspectors were not being allowed into the site in Douma.

"I can guarantee that Russia has not tampered with the site," Lavrov told BBC's Hardtalk programme.

He also said that the evidence of a chemical attack carried out by Syrian forces cited by Britain, France and the United States had been based "on media reports and social media".

Lavrov denied that any chemical attack had taken place, telling the BBC: "What did take place was the staged thing".

Russia has accused Britain of being involved in staging the attack.

The Organisation for the Prohibition of Chemical Weapons (OPCW) was holding a closed-door meeting at its headquarters in The Hague on Monday to discuss the alleged chemical attack, following air strikes on Syria by London, Paris and Washington on Saturday.

Britain's embassy to the Netherlands earlier on Monday said Russia and Syria have not yet allowed a fact-finding mission from the world's chemical weapons watchdog to enter Douma.

British ambassador Peter Wilson also urged the meeting "to act to hold perpetrators to account", saying failure to do so "will only risk further barbaric use of chemical weapons, in Syria and beyond".