Russia’s President Vladimir Putin has rubbished U.S. claims that the Syrian government used chemical weapons and challenged Washington to present proof.

Breaking his silence on the latest escalation of the Syrian crisis, Mr. Putin dismissed as “utter nonsense” the U.S. accusations of government troops having used poisonous gas in a war that they were winning anyway.

“Syrian government troops are on the offensive; in several regions they have surrounded the rebels. In these conditions, it is utter nonsense to give a trump card to those who are calling for a military intervention,” Mr. Putin told reporters in Vladivostok on Saturday.

“That is why I am convinced that [the chemical attack] is nothing more than a provocation by those who want to drag other countries into the Syrian conflict, and who want to win the support of powerful international players, above all, the United States. I have no doubts at all about it.”

The Russian leader demanded that Washington produce hard evidence that Syria was behind the chemical attacks.

“Saying that they have such evidence but it is classified and they cannot show it to anyone does not stand up to criticism,” Mr. Putin said.

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