The weapons inspectors' report was never intended to identify the culprit of the chemical attack

UN inspectors will point the finger of blame at the Assad regime for a deadly chemical weapons strike that threatens to drag the US and other Western powers into the Syria conflict.

The report, due to be published on Monday, will include a wealth of evidence that a chemical nerve agent was used in the attack, according to sources.

Such a finding will throw President Putin on to the back foot as Russia and the US wrangle over how to force President Assad to rid himself of his chemical arsenal.

Mr Putin used an article in The New York Times yesterday to challenge the US, French and British version of the August 21 poison gas massacre.

“There is every reason to believe it was used