France and Britain said Tuesday they would soon submit to the UN Security Council a resolution that slaps sanctions on Syrian authorities responsible for the use of chemical weapons.

A joint investigation by the United Nations and the Organization for the Prohibition of Chemical Weapons (OPCW) found that several units of the Syrian army had used toxic weapons against three villages in northern Syria in 2014 and 2015.

The jihadist Islamic State group also used mustard gas in an attack in Syria, concluded the watchdog team, officially known as the Joint Investigative Mechanism.

The mandate for the JIM investigation was recently extended for another year to allow it to investigate chemical attacks that have been reported in Syria this year.

The ambassadors of Britain and France to the United Nations said Tuesday that they would propose a draft Security Council resolution to the other 13 members of the council.

"The JIM was very clear that the Syrian regime did use chemical weapons," said British ambassador Matthew Rycroft, condemning "that abhorrent use."

"We'll propose with the UK a draft resolution sanctioning those responsible for the use of chemical weapons based on the JIM report," said French ambassador Francois Delattre.

"The Security Council needs to take its responsibility on this... it is crucial for the non-proliferation regime and for the credibility of the council," Delattre said.

The French ambassador noted "the conclusions of the JIM are clear with respect to both the regime and Daesh," another acronym for the Islamic State group.

The two ambassadors did not indicate a timetable for the presentation of the draft resolution and a vote on the text.

The action could run into a veto by Russia, which remains skeptical about the conclusions of the JIM investigators regarding its Syrian ally.

Another way to punish those responsible for the use of chemical weapons in Syria would be to take the case to the International Court of Justice, which settles legal claims such as war crimes and crimes against humanity.

The UN Security Council could refer the case to the ICJ but its attempts so far have been blocked by veto-wielding Russia and China.