Russia on Friday criticised a United Nations report which blamed a sarin gas attack in Syria on Bashar al-Assad's regime, with a deputy foreign minister saying it contained inconsistencies and unverified evidence.

Earlier in the week Russia vetoed a US-drafted resolution that would have extended for one year an investigation looking into chemical weapons attacks in Syria.

"Even the first cursory read shows that many inconsistencies, logical discrepancies, using doubtful witness accounts and unverified evidence... all of this is still (in the report)," Deputy Foreign Minister Sergei Ryabkov told Interfax news agency.

Ryabkov said other nations were seeking to use the report to "resolve their own strategic geopolitical issues in Syria".

Russia would analyse the findings and publish a response soon, he added.

More than 80 people died on April 4 when sarin gas projectiles were fired into Khan Sheikhun, a rebel-held town in the Idlib province of northwestern Syria.

Syria and its ally Russia had suggested that rebels may have detonated an explosion on the ground but the UN panel confirmed Western intelligence reports that blamed the regime.

British Foreign Secretary Boris Johnson accused Russia of trying to "disrupt efforts to get to the truth".

"I call on Russia to stop covering up for its abhorrent ally and keep its own commitment to ensure that chemical weapons are never used again," he said.

Human Rights Watch, which has called for sanctions on Damascus over chemical weapons, said that all countries had an interest in signalling that such attacks would not be tolerated.

"Russia called for an independent investigation and here is the result," said Ole Solvang, deputy emergencies director at HRW.

"The question now is whether Russia will support accountability for the violation of these international norms or whether it will sacrifice principle to protect its Syrian ally."

France welcomed the results of the investigation.

"Impunity is not acceptable," Foreign Minister Jean-Yves Le Drian said.

The expert panel's report came as the United States renewed its warning that Assad has no role in Syria's future.

Source: AFP