By Nathan Morley
The U.S. State Department insists that Russia has tried to block an international investigation into the alleged chemical attack in Syria.
The investigators from the Organization for the Prohibition of Chemical Weapons arrived in Syria on Saturday, but so far have not been able to begin their work in Douma.
Russia's Deputy Foreign Minister said the mission was not allowed in because the United Nation’s Department for Safety and Security had not given its approval.
But U.N. officials in New York rejected the claim.
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.