PARIS, April 1, 2008 (AFP) - French lawmakers were gearing up for a stormy debate in parliament Tuesday after the leftist opposition balked at President Nicolas Sarkozy's plan to send more troops to Afghanistan.

Bolstered by an opinion poll showing 68 percent of the French disapprove of Sarkozy's decision to send reinforcements, the Socialists are calling for a vote on the mission during the debate in both houses of parliament.

Prime Minister Francois Fillon, who is to address lawmakers, rejected calls for a vote, saying the decision to take part in the NATO mission in Afghanistan was taken by a previous government in 2001 without one.

Fillon argued that Kabul could fall to Afghanistan's Taliban militia unless the NATO mission was strengthened, resulting in 'real defeat for all those who defend freedom.'

'The situation in Afghanistan is improving around Kabul but it is worsening in the other regions,' Fillon told French radio on Tuesday, on the eve of a NATO summit in Bucharest that is to shore up the mission in Afghanistan.

The Socialists were due to file a no confidence motion against the government after the debate -- a mainly symbolic move since Sarkozy's ruling right-wing camp holds a firm majority in both houses of parliament.

The parliamentary debate comes amid sharp criticism from the left and within the ranks of Sarkozy's governing right-wing party over France's shift toward a more US-friendly stance.

Critics lament that France is aligning itself with Washington and recklessly doing away with the independent foreign policy that has been its hallmark since the post-war period under Charles de Gaulle.

Sarkozy angered politicians at home when he announced the reinforcements in an address to the British parliament last week, although the precise makeup of the new force is to be unveiled by the president at the NATO summit.

Sources in Paris have said 1,000-plus troops could be sent to shore up the current 1,600-strong French contingent that is deployed mostly in Kabul and the surrounding area. Some 100-200 French special forces could also take part.

Public support for deepening France's involvement in Afghanistan is weak, according to a recent BVA poll which showed only 15 percent back the move, against 68 percent who disapprove of the decision.

Faced with criticism that the troops were a sop to Washington, Fillon recalled that France had set conditions for the reinforcements including increased aid and reconstruction efforts, and troop commitments from other countries.

He said a revamped training programme for the Afghan army could allow it to take control of Kabul by the summer of 2009.

The opposition Socialists and some members of the government Union for a Popular Movement (UMP) party have linked the French reinforcements to Afghanistan to France's return to NATO command.

Sarkozy last year raised the possibility of France rejoining NATO's integrated command, which it left in 1966 when De Gaulle rejected US dominance of the alliance.

Socialist leader in parliament Jean-Marc Ayrault accused Sarkozy of seeking to please 'the American big brother, (and) be a good boy' by committing French troops to Afghanistan.

'Our country has values that it must defend. When France refused to engage in the war in Iraq, it was right and earned respect,' said Ayrault in an interview to Liberation.

Amid much public debate over the mission, Fillon was forced to admit he committed a blunder when he said there had never been a vote in parliament on deploying troops abroad.

Former president Francois Mitterrand in 1991 had asked parliament to approve France's involvement in the Gulf War.

Under the French constitution, defence issues are the exclusive purview of the president, which means he is not required to seek approval from parliament to send troops abroad.