Russia said Friday it will use its veto to block a proposed UN resolution drafted by the United States, France and Britain that would impose sanctions on Syria for the use of chemical weapons.

"I just explained our position very clearly to our partners. If it is tabled we will veto it," Russian Deputy Ambassador Vladimir Safronkov told reporters following a closed-door meeting of the Security Council.

The United States, France and Britain are pushing for a vote early next week on the proposed resolution that would slap sanctions on Syrians deemed responsible for chemical attacks in the nearly six-year war.

Safronkov rejected the measure as "one-sided," saying it was based on "insufficient proof" and contradicted "the fundamental principle of presumption of innocence until the investigation is over."

Russia has used its veto six times to shield its Damascus ally from any punitive action by the Security Council.

The draft resolution follows a UN-led investigation which concluded in October that the Syrian military had carried out at least three chlorine attacks on opposition-held villages in 2014 and 2015.

The joint panel of the United Nations and the Organization for the Prohibition of Chemical Weapons (OPCW) also found that Islamic State (IS) militant group had used mustard gas in an attack in 2015.

US Ambassador Nikki Haley said she was not swayed by the Russian arguments.

"How much longer is Russia going to continue to babysit and make excuses for the Syrian regime?" she said.

"People have died by being suffocated to death. That's barbaric."

"You are either for chemical weapons or you are against it," she added.

The draft resolution, seen by AFP, would impose a global travel ban and assets freeze on 11 Syrians, mostly military officials, and 10 entities linked to chemical weapons development.

It would also ban the sale, supply or transfer of helicopters and related materiel, including spare parts, to the Syrian armed forces or the government.

The UN-OPCW panel found that Syrian air force helicopters dropped chlorine barrel-bombs on the villages of Qmenas, Talmenes and Sarmin in 2014 and 2015.

Chlorine use as a weapon is banned under the Chemical Weapons Convention, which Syria joined in 2013 under pressure from Russia.

The Syrian government has repeatedly denied using chemical weapons in the war that has killed 310,000 people since March 2011.