By Nathan Morley
The Organization for the Prohibition of Chemical Weapons already has a team probing what happened in Douma, but reports of their progress remains unknown.
On Monday, Russia denied interfering with evidence at the site of the suspected chemical weapons attack.
The US, Britain and France claim Syrian President Bashar al-Assad's army was behind the attack, a charge which Syria and Russia deny.
"I can guarantee that Russia has not tampered with the site,” Russian Foreign Minister Sergei Lavrov told British television.
Moscow also expressed anger that the three powers acted before Organization for the Prohibition of Chemical Weapons were allowed start their investigation in Douma.
On Saturday, the United States, Britain and France insisted that their strikes in Syria were legal and justified, brushing off Moscow's charge that they had violated international law.
They said the air strikes targeted three separate targets linked to the Syrian governments chemical weapons programme.
Russia said the provisions of the United Nations charter had also been broken.