French Foreign Minister Laurent Fabius said Saturday the inspectors should be granted immediate access to the site "if the Syrian regime has nothing to hide."
"All the information available to us converge to say that there has been a chemical massacre in Syria, near Damascus, and to indicate that it is the regime of Bashar al-Assad who is at the origin," Fabius told reporters after meeting with Palestinian officials in the West Bank city of Ramallah.
Earlier, British Foreign Secretary William Hague suggested the delay in granting access was suspicious.
"This is not something that a humane or civilized world can ignore," Hague said. Our priority is to make sure the world knows the facts of what has happened, and that means the U.N. team that is in Damascus, only 20 minutes away, being able to get there and to investigate."
Rapid access is critical, since any evidence would deteriorate "over a matter of days," Hague said.
The Syrian government has denied using chemical weapons.