Russia and France's foreign ministers have disagreed over who is to blame for the chemical weapons attack in Syria, reports the BBC.
After talks in Moscow, France's Laurent Fabius said the UN's report into the August incident left no doubt that the Syrian government was responsible.
But Russia's Sergei Lavrov said Moscow had "very serious grounds" to believe the attack had been a provocation by rebel forces.
Mr Fabius is pressing Russia to support a Security Council resolution on Syria.
On Monday, UN weapons inspectors said in much-anticipated report that the nerve gas sarin had been used against civilians on a relatively large scale in a suburb of Damascus on 21 August.
UN Secretary-General Ban Ki-moon has described the attack as a war crime.
US allegations that the Syrian government was responsible had led to threats of military action.
But under a deal brokered at the weekend by Russia and the US, Syria will disclose its chemical weapons within a week and eliminate them by mid-2014.
France is now trying to win support for a UN resolution with the threat of serious consequences if this does not happen.
Russia, which is Syria's strongest ally, says the government of President Bashar al-Assad should first be given the chance to give up its chemical weapons.
Read more of this report from the BBC.