Reuters- Iran's Foreign Minister Mohammed Javad Zarif, pointing to Sunni Islamist militants in Syria fighting against its allies in Damascus, told the Munich Security Conference that the use of chemical weapons could never be condoned.

Damascus, an ally of majority-Shia Iran, this week rejected a recent Human Rights Watch report that said its military and allied forces had used chemical weapons during their capture of Aleppo last year. It instead accused anti-government fighters of using chemical weapons.

"The use of chemical weapons can never be condoned ... Unfortunately the terrorist organisations Nusra and Daesh (Islamic State) still possess chemical weapons," Zarif said.

A U.N.-Organisation for the Prohibition of Chemical Weapons (OPCW) inquiry assigned to identify organisations and individuals responsible for the chemical attacks concluded last October that Syrian government forces had used chlorine as a chemical weapon at least three times in 2014-15. Islamic State militants, it said, had used sulphur mustard gas in one attack.

The U.N. Security Council extended the mandate of the inquiry, known as the Joint Investigative Mission (JIM), until November this year. It is due to issue its next report by Saturday.

The United States last month blacklisted 18 senior Syrian officials it said were connected to the country's weapons of mass destruction programme, after an international investigation found Syrian government forces were responsible for chlorine gas attacks against civilians.

Human Rights Watch Executive Director Ken Roth told delegates the issue was likely to be discussed between major powers in the coming days.

"Another big test coming up is in the Security Council, probably just this next week, of the so-called joint investigative mechanism established by the Security Council," Roth said.

"So, the question comes up, what's next? The French have taken the lead in drafting a resolution and put it on the table imposing sanctions for Syria's use of chemical weapons and Russia is threatening to veto it."

France said on Feb 14 that the U.N. had to respond over the use of chemical weapons with a resolution that would punish those responsible for repeated attacks.

A French diplomatic source said that Paris was still looking for the right time to put the resolution to a vote but that it was working on a new text in the hope of ensuring it was supported by Assad ally, Russia.

"We have again started work on a text with our partners," the source said.

(Reporting By Shadia Nasralla and Vladimir Soldatkin; Writing by John Irish; Editing by Andrew Bolton)