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.

"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.