Member countries of the Organisation for the Prohibition of Chemical Weapons agreed in June to allow the body to identify the perpetrators of chemical attacks, but the new powers are strongly opposed by Moscow and Damascus.

"The recruitment process of the members of the team is under way and is currently being finalised," OPCW chief Fernando Arias said in a statement to The Hague-based body on Tuesday but not released until Wednesday.

Arias said the so-called Investigation and Identification Team (IIT) "will become fully operational in the coming weeks".

Western states immediately called for the team to start work on identifying the culprits behind a deadly attack in the Syrian town of Douma in April 2018.

The OPCW said in a report on March 2 that chlorine was likely used in the attack, which it said killed more than 40 people.

The report however did not apportion blame as it was not in the watchdog's mandate at the time.

Syria and Russia rejected the report, saying the Douma incident -- which sparked western airstrikes against the regime of President Bashar al-Assad -- was faked.

Canada's delegation to the watchdog tweeted that it "expects Douma case to be referred to OPCW Investigation/Identification Team. Those responsible must be held accountable".

Britain said that it "look(s) forward to further investigation by IIT to identify those responsible".

The West pushed through the new blaming powers after a string of chemical incidents in Syria, as well as a nerve agent attack on Russian former double agent Sergei Skripal in the British city of Salisbury in March 2018.

Russia tried last year to block the budget for the OPCW if it included funding for the investigations team.

China and Iran have also opposed the new powers.

OPCW chief Arias said the investigations team so far had 400,000 euros of funding but needed a further 1.13 million euros for the rest of 2019.

He added that the watchdog had discussed the investigations team with Syria during talks in February on destroying Damascus's chemical weapons stocks, and would now "seek to secure the cooperation of the Syrian Government" for probes.