MOSCOW, Russia (AFP) - The Russian military on Friday (April 3) said it had proof that an alleged chemical weapons attack in Syria's Eastern Ghouta was staged on orders from London.

Russian defence ministry spokesman Igor Konashenkov said the military had "proof that testifies to the direct participation of Britain in the organising of this provocation in Eastern Ghouta".

He said Britain had told the White Helmets, who act as first responders in rebel-held areas, to fake the suspected chemical attack in the town of Douma.

London put "powerful pressure" on the civil defence organisation, Konashenkov said.

He said the attack was staged on April 7 to coincide with military action by Syrian government forces, after the rebel group Jaish al-Islam that long controlled Eastern Ghouta carried out shelling of Damascus from April 3 to 6.

Britain's UN Ambassador Karen Pierce called the spokesman's remarks "grotesque" and "a blatant lie."

"It's some of the worst piece of fake news we've seen yet from the Russia propaganda machine," Pierce told reporters at UN headquarters in New York.

"I would like to take this opportunity to state categorically that... Britain has no involvement and would never have any involvement in the use of a chemical weapon."

Russia has repeatedly accused rebels of staging or spreading rumours of chemical attacks, but the involvement of Britain is a new claim.

It comes as London has blamed Moscow for a nerve agent attack on a former double agent and his daughter in the English city of Salisbury last month.

In March Russia's General Staff said that rebels were planning a "provocation" in Eastern Ghouta with women and children set to play victims of a chemical attack.

President Vladimir Putin later referred to this claim, saying on April 4 that Russia had "irrefutable proof" that rebels were planning an attack with "poisonous substances".