French Prime Minister Jean-Marc Ayrault urged lawmakers on to back military action against the Syrian regime in response to "the most massive and terrifying use" of chemical weapons this
The debate came as Syria's deputy foreign minister Faisal Muqdad ridiculed France as an American stooge.
"It's shameful that the French president... says 'if Congress approves, I go to war, otherwise I won't go', as if the French government had no say in the matter," Muqdad said in an exclusive interview with AFP.
Opening a fiery debate on France's reaction to the alleged deadly gas attack, Ayrault said it was "undeniable" that the regime had used chemical weapons to kill up to 1,500 people in the August 21 assault near Damascus.
"To not react would put peace and security in the entire region in danger," Ayrault said. "What message would we send to other regimes? And I'm thinking here, like you, of Iran and North Korea."
He also said not reacting militarily would "close the door on a political solution" to the conflict.
President Francois Hollande's Socialists, who enjoy a majority in the National Assembly, are largely supportive of strikes. But other leading parliamentary factions voiced opposition, including the main opposition
The UMP said it would not support military action without the backing of the United Nations or a broad international coalition.
"Can France seriously, without any European ally, leap head down into an adventure of this sort?" asked Christian Jacob, the head of the UMP's faction in the National Assembly. "We don't think so."
Andre Chassaigne, the head of the Left Front coalition, said he was "vigorously opposed" to intervention as it would be "illegal, unjustified and unfounded in terms of international law."
No vote was to take place after the debate, as Hollande does not need parliamentary approval to launch military action.
But amid widespread scepticism in France over military strikes, the government has launched a major effort to bolster support.
Ayrault said there was "no question" of France putting troops on the ground in Syria but that some form of military reaction was essential.
"Our message is clear: using chemical weapons is unacceptable. We want to both punish and dissuade," he said, calling last month's attack "the most massive and terrifying use of chemical weapons at the beginning of this century".
Many French lawmakers, including some Socialists, are clamouring for a full vote on military action. A poll on the eve of the debate also showed nearly three quarters of the French wanting parliament to have a say.
Hollande's government has not ruled out a vote, but he will be keen to avoid an embarrassing rejection of military strikes like the one suffered last week by British Prime Minister David Cameron.
France has repeatedly vowed to "punish" Assad for the alleged chemical weapons attack and this week released an intelligence report pinning the blame for the assault on the regime.
The French debate comes as US President Barack Obama lobbies Congress to back US strikes when it returns from its summer break .
France has emerged as the key US ally in taking action against Assad's regime, after Britain's House of Commons rejected military action.
The divisions in France over action in Syria are in sharp contrast to the widespread support Hollande enjoyed when he launched a military intervention in Mali earlier this year.
The Mali operation, which saw French troops push back Islamist rebels who had seized the west African country's vast desert north, was launched without any thought of holding a parliamentary vote. Four months later, its continuation was backed without any votes against.
The Mali intervention was widely backed by the public however, unlike a military intervention in Syria, which a recent poll showed is opposed by 64 percent of the French.