WASHINGTON (AP) - A senior administration official says there is “very little doubt” that a chemical weapon was used by the Syrian regime against civilians in an incident that killed at least a hundred people last week.

The official says Sunday that the U.S. intelligence community based its assessment given to the White House on ``the reported number of victims, reported symptoms of those who were killed or injured, and witness accounts.'' The official spoke on condition of anonymity because the official was not authorized to speak publicly.

The official says the White House believes the Syrian government is barring a U.N. investigative team immediate access to the site of a reported Aug. 21 attack in the Damascus suburbs in order to give the evidence of the attack time to degrade.