The Syrian president issued a dire warning that any Western military intervention could lead to “regional war” and would harm “the interests of France,” Telegraph.co.uk reported.

“Whoever accuses must provide proof. We have challenged the United States and France to provide the slightest proof. (US President Barack) Obama and (French president François) Hollande have been incapable (of doing so) even to their own people,” Assad told French newspaper Le Figaro in an exclusive interview.

He questioned the “logic” of claims that his forces carried the August 21 attack outside Damascus, which the US said killed 1,429 people.

“Supposing our army wishes to use weapons of mass destruction. Is it possible that it would do so in a zone where it is located and where (our) soldiers were wounded by these arms, as United Nations inspectors have noted during visits to hospitals where they were treated? Where is the logic?,” he asked.

Describing the Middle East as a “powder keg” whose “fuse is getting shorter”, he warned it would “explode” if Western forces struck Syria. “Nobody knows what will happen (after such strikes). Everyone will lose control of the situation when the powder keg explodes. Chaos and extremism will spread. The risk of a regional war exists,” he warned.

The Syrian leader then ratcheted up pressure on France to steer clear of military action two days ahead of a parliamentary debate on the issue. Two thirds of French people are against participating, according to a poll out on Saturday.

Assad said: “Whoever contributes to financially or militarily to bolstering terrorists is an enemy of the Syrian people. Whoever is against the interests of Syria and its people is an enemy.”

“The French people are not our enemy. If the policies of the French state are hostile to the Syrian people, this state will be its enemy. This hostility will end when the French state changes its policies. There will be repercussions – negative, of course – against the interests of France,” he warned.

Mr Assad accused the US president of being a weak leader.

“If Obama was strong, he would have said publicly: ‘We have no evidence of the use of chemical weapons by the Syrian State’. He would have said publicly: ‘The only way to proceed is through UN investigations. We therefore refer everything to the Security Council.’ But Obama is weak because he is facing pressure from within the United States,” he said.

Mr Assad said it was too late for dialogue with rebel opponents.

“We are fighting terrorists. Eighty to 90 per cent of those we are fighting belong to Al Qaeda. They are not interested in reform or in politics. The only way to deal with them is to annihilate them. Only then will we be able to talk about political measures,” he said.