Following its investigation, backed by similar reports from its allies including Britain and France, the United States has said that the Assad regime in Syria has used chemical weapons on a small scale resulting in death of between 100 to 150 people.

"Following a deliberative review, our intelligence community assesses that the Assad regime has used chemical weapons, including the nerve agent sarin, on a small scale against the opposition multiple times in the last year.

Our intelligence community has high confidence in that assessment given multiple, independent streams of information," Ben Rhodes, the Deputy National Security Advisor to the US President, said yesterday.

"The intelligence community estimates that 100 to 150 people have died from detected chemical weapons attacks in Syria to date; however, casualty data is likely incomplete," he said.