PARIS (REUTERS) - France said on Tuesday (April 17) it was very likely that evidence was disappearing from the location of a suspected poison gas attack in Syria and it called for international inspectors be given full and quick access to the site.

US, British and French forces pounded Syria with air strikes early on Saturday in retaliation for the suspected April 7 chemical weapons attack in Douma, which they blame on Syrian President Bashar al-Assad's government.

Inspectors from the Organisation for the Prohibition of Chemical Weapons (OPCW) travelled to Syria last week to inspect the site, but have yet to gain access to Douma, which is now under government control after rebels withdrew.

"As of today, Russia and Syria still refuse to give inspectors access to the site of the attack," the French foreign ministry said in a statement.

"It is very likely that proof and essential elements are disappearing from this site."

Relief organisations say dozens of men, women and children were killed in the attack.

"It is essential that Syria finally gives full, immediate and unfettered access to all of the OPCW's demands, whether to visit sites, interview people or consult documents."

US Ambassador Kenneth Ward on Monday said at an OPCW meeting in The Hague that Russia may have tampered with the evidence.

"It is our understanding the Russians may have visited the attack site," he said in comments at a closed-door meeting which were obtained by Reuters.

"It is our concern that they may have tampered with it with the intent of thwarting the efforts of the OPCW Fact-Finding Mission to conduct an effective investigation," he said.