UNITED NATIONS: The United Nations Security Council will likely vote on a resolution to blacklist 11 Syrian military commanders and officials over chemical weapons attacks as early as next week, diplomats said on Thursday.

The draft resolution also seeks to ban the sale or supply of helicopters to the Syrian government and to blacklist 10 government and related entities involved in the development and production of chemical weapons and the missiles to deliver them.

It calls for an asset freeze and travel ban for the individuals and entities across all UN member states.

A joint inquiry by the United Nations and the Organization for the Prohibition of Chemical Weapons, or OPCW, found that Syrian government forces were responsible for three chlorine gas attacks and that Islamic State militants had used mustard gas, according to reports seen by Reuters in August and October.

Syrian President Bashar al-Assad's government has denied its forces have used chemical weapons.

Chlorine's use as a weapon is banned under the Chemical Weapons Convention, which Syria joined in 2013. If inhaled, chlorine gas turns into hydrochloric acid in the lungs and can kill by burning lungs and drowning victims in the resulting body fluids.

The UN vote could coincide with talks between representatives of Assad's government and his opponents with UN mediator Staffan de Mistura, which started on Thursday in Geneva.

The Security Council diplomat said the draft resolution would be brought to a vote next week unless a "really compelling argument" against it emerged from the talks.

A Western diplomat said the new US administration was now co-sponsoring the resolution, and consultations on it could start on Friday at the Security Council.

Former US President Barack Obama's administration had handed over the drafting of the resolution to France and Britain as it had not wanted to complicate its talks with Russia over Syria.

Both diplomats were speaking on condition of anonymity and said it would likely be vetoed by Russia, the main foreign backer of Assad's government.

"With Geneva on at the same time, we think this resolution sends a strong message," one diplomat said.

The US and Russian delegations to the United Nations did not immediately respond to a request for comment.

When a draft was discussed informally by the Security Council last December, Russia made clear it would not support the text.

Following the UN-OPCW investigation, the United States in January blacklisted 18 senior Syrian officials it said were connected to the country's weapons of mass destruction program.

At least nine of the 11 officials in the UN draft resolution were also blacklisted by the US government.