France to Give Lawmakers Proof Syria Regime behind Chemical Attack

France was set Monday to provide what it says is clear evidence that the Syrian regime was behind a devastating chemical attack, as Western leaders bid to overcome widespread skepticism to military action.

With U.S. President Barack Obama also lobbying Congress to back strikes, the Syrian regime said it remained on alert for a possible attack, urging the United Nations to "prevent any aggression" against it.

NATO chief Anders Fogh Rasmussen said he was personally convinced the chemical attack had taken place and that Syrian President Bashar Assad's regime was responsible.

He called for a response that would "send a very clear message" against the use of chemical weapons, but said any military action should be "very short, sharp (and) tailored".

French government sources said evidence proving the regime's involvement in the attack would be provided to top lawmakers at a meeting with Prime Minister Jean-Marc Ayrault at 1500 GMT.

"We are going to give parliamentarians everything that we have -- classified until now -- so that each of them can take into account the reality of this unacceptable attack," Ayrault said.

A government source said lawmakers would be given "evidence of different kinds that will allow the regime to be clearly identified as responsible for the August 21 chemical attack".

The French parliament is to hold a debate Wednesday on taking action on Syria, where more than 110,000 people have been killed in violence since an uprising against the regime began in March 2011.

Government sources said Sunday that French intelligence had compiled information showing the Syrian regime had stockpiled more than 1,000 tonnes of chemical agents, including sarin gas, mustard gas and more powerful neurotoxic agents.

Hollande has vowed to "punish" Assad for the alleged gas attack, which Washington says killed more than 1,400 people.

The French president can order military action without parliamentary approval but some lawmakers have urged Hollande to put the issue to a vote, as Obama is doing in the United States.

France has emerged as the main U.S. ally in the Syria crisis after the British parliament, in a shock move, rejected plans for military action mooted by Washington.

Britain's government said Monday it had "no plans" to hold a second parliamentary vote on joining military action.

But public opinion in both France and the U.S. is deeply skeptical, and in a surprise move Obama put off threatened missile strikes, saying Saturday he would seek approval from Congress first.

That pushed back any U.S.-led military action until at least September 9, when U.S. lawmakers return from their summer break.