moscow // Russia and France clashed on Tuesday over who launched a chemical weapons attack on the outskirts of Damascus last month.

United Nations inspectors have confirmed that sarin nerve gas was used and the United States and other western powers say the Assad regime committed the atrocity in which up to 1,400 Syrians died.

The Russian foreign minister Sergei Lavrov said there were “serious grounds” to believe the attack was carried out by rebel forces to provoke western military intervention in the Syrian civil war.

“We want an impartial, objective and professional investigation of the August 21 events,” Mr Lavrov said after a meeting in Moscow with the French foreign minister Laurent Fabius.

“We have the most serious grounds to consider it a provocation. Some of our partners said dictatorially that only the regime could use such weapons, but the truth must be established.”

Mr Fabius said: “When you look at the amount of sarin gas used, the vectors, the techniques behind such an attack, as well as other aspects, it seems to leave no doubt that the regime is behind it.”

The dispute came as diplomats from the US, Russia, France, Britain and China, the five permanent members of the UN Security Council, meet in New York to discuss a resolution on eradicating Syria’s chemical arsenal amid differences over whether it should be backed up by the threat of force.

Nearly an hour of initial talks ended with an agreement to meet again on Wednesday, diplomats said.

The draft resolution was drawn up by the US, Britain and France and is based on a US-Russian agreement reached at the weekend that requires the Bashar Al Assad’s regime to fully disclose its chemical weapon stockpiles and for these to be handed over and disposed of by the middle of next year.

However, the US, Britain and France have been at odds with Russia, an ally of the Assad regime, over whether the resolution should be under Chapter 7 of the UN charter, which would make it enforceable by military or non-military means such as sanctions.

The UN secretary general Ban Ki-moon said the “most effective” way was under Chapter 7.

While in principle all Security Council resolutions are legally binding, Mr Ban said, “in reality, we need clear guidelines under Chapter 7”.

The president of the opposition Syrian National Coalition added his voice to calls for the Security Council resolution to be adopted under Chapter 7, allowing use of force to cripple Syria’s “war machine”.

“Ending the killing of Syrian people is only possible by stopping the regime’s war machine and barring it from using its aviation, missiles and artillery, and depriving it of its chemical weapons,” Ahmed Jarba said.

A deal to remove Syria’s chemical arms is seen as a precursor to peace talks to end a bloody civil war that has lasted more than two years and claimed more than 100,000 lives. In the latest violence, a car bombing at the rebel-controlled Bab Al Hawa crossing into Turkey killed at least seven people and wounded 20 others.

International action against Syria’s chemical weapons was prompted by the use of nerve gas in Damascus suburb on August 21 that killed hundreds of civilians, although the exact death toll has not been confirmed.

A US threat to launch punitive missile strikes was averted by the US-Russian deal on a timetable for removing Syria’s chemical weapons.

The US, British and French envoys to the UN also said the UN investigators’ conclusion that surface-to-surface rockets were used in the attack point to the regime rather than its less well armed opposition.

* Reporting by Reuters and the Associated Press