France: Syrian government 'behind chemical attack'
France says the chemical attack near Damascus last month "could not have been ordered and carried out by anyone but the Syrian government".
A report presented to parliament by Prime Minister Jean-Marc Ayrault says the assault on 21 August involved the "massive use of chemical agents".
It concludes that at least 281 deaths can be attributed to the attack.
France and the US are pushing for punitive military action, which the UK parliament rejected last week.
Syrian President Bashar al-Assad has again denied carrying out a chemical attack, telling the French newspaper Le Figaro it would have been "illogical".
He also warned that foreign military action could ignite the "powder keg" of the wider region.
The chemical attack took place in the Ghouta, an agricultural belt around the capital, Damascus.
The US put the death toll at 1,429, including 426 children and has blamed the Syrian government, based on its intelligence.
On Monday Mr Ayrault made public France's nine-page report into the incident, drawn up by military and foreign intelligence services.
It says Syria's arsenal of chemical weapons is "massive and diverse", comprising "several hundred tons" of the nerve agent sarin and "dozens of tons" of the most toxic known agent, VX.
The Syrian army had already used chemical weapons, including sarin, against the population several times, says the report, but on 21 August it launched an attack which involved "massive use of chemical agents".
The use of chemical weapons can only be authorised by President Assad or "certain influential members of his clan", says the report, while opposition forces lack the capacity to carry out such a large-scale chemical attack.
After his meeting with MPs, Mr Ayrault told reporters: "France is determined to penalise the use of chemical weapons by Assad's regime and to dissuade with a forceful and firm response."
He said France would not act alone and that President Francois Hollande was "continuing his work of persuasion to bring together a coalition".
President Hollande is constitutionally able to order an attack without parliamentary approval.
French MPs are due to debate the issue in an extraordinary session of parliament on Wednesday. However, Mr Ayrault has ruled out a vote.
UK MPs voted last week against taking part in military action.
The US Congress will vote after it reconvenes next week, and White House officials have said that when it comes to a vote, they believe there will be enough support for the president.
Senator John McCain, a long-time advocate of arming the Syrian rebels, said he believed it would take time to convince the American public of the need to intervene.
But he warned it would be "catastrophic" if Congress were to go against President Obama and vote against intervention.
Mr Obama has often said that using them would cross a "red line" that would prompt US intervention.
"It would undermine the credibility of the United States of America and the president of the United States. None of us want that," he said.
Nato Secretary General Anders Fogh Rasmussen said on Monday he was personally convinced that a chemical attack took place and that the Assad government was responsible.
But he added that he did not envisage any further role for Nato, saying he would expect any military response to be "a very short, measured, targeted operation" and that the alliance's resources would not be needed.
Meanwhile fighting has continued across Syria, in a conflict which has already left an estimated 100,000 people dead since 2011.
In other developments:
- A BBC poll shows about three-quarters of the British public believe MPs were right to reject UK military action in Syria in a vote last week
- UK Deputy Prime Minister Nick Clegg said parliament will not vote again if stronger evidence of a state chemical attack emerges
- Russia's Foreign Minister Sergei Lavrov says the US intelligence blaming Damascus is "absolutely unconvincing"
Forces which could be used against Syria:
•Five US destroyers - USS Gravely, USS Ramage, USS Barry, USS Mahan and USS Stout - are in the eastern Mediterranean, equipped with cruise missiles. The missiles can also be fired from submarines, but the US Navy does not reveal their locations
•Airbases at Incirlik and Izmir in Turkey, and in Jordan, could be used to carry out strikes
•Two aircraft carriers - USS Nimitz and USS Harry S Truman are in the wider region
•French aircraft carrier Charles de Gaulle is currently in Toulon in the western Mediterranean
•French Rafale and Mirage aircraft can also operate from Al-Dhahra airbase in the UAE