Russian Foreign Minister Sergei Lavrov said a reported chemical attack in Syria was staged by foreign agents.
The US and France have said they have proof it took place, and, alongside the UK, they are considering launching military retaliation against Syria.
Russia, a Syrian ally, has warned the US that air strikes risk a new war.
Independent chemical weapons inspectors are en route to East Ghouta province to look for evidence. They are expected to arrive on Saturday.
During a press briefing on Friday, Mr Lavrov said he had “irrefutable evidence” that the attack was staged as part of a “Russophobic campaign” led by one country, which he did not name.
Russia has requested a United Nations meeting in New York later in the day, but this has not yet been confirmed.