Nicolas Sarkozy's proposal, widely seen as part of his campaign for the presidential election next year, has attracted criticism from left-wing parties and church leaders, and prompted the far-right to step up its anti-immigrant line.

But it puts him at the centre of attention at a time when Dominique de Villepin, the prime minister, has been weakened by his recent climbdown over labour law reform and a growing scandal about an alleged smear campaign against Sarkozy.

Sarkozy, the son of a Hungarian immigrant, has had to defend himself against charges that he is running a xenophobic drive to take votes from Jean-Marie Le Pen, the far-right National Front leader who launched his presidential campaign on Monday.

Thierry Mariani, a deputy and Sarkozy ally, said: "All democrats should welcome it if the National Front's score falls."

Le Pen shocked France in 2002 by finishing second to Jacques Chirac in the first round of presidential elections.

Attracting skilled workers

Sarkozy says the bill, to be discussed on Tuesday, aims to attract a new generation of skilled workers who would embrace French values and traditions, thus easing the tense race relations that led to last autumn's suburban riots by youths mostly of immigrant origin.

A labour law reform sparked 
mass protests in March

It would create a three-year "skills and talents" residence permit to attract skilled workers. It would also make it harder for resident immigrants to bring family, force newcomers to take French and civics lessons, and end their automatic right to a long-term residence permit after 10 years in France.

Sarkozy says his bill will allow France to select its immigrants, as other industrialised countries do, rather than take anyone who comes. This should help to reduce racism, he says.

Left-wing critics say the law will not work, will stigmatise foreigners, discriminate against the poor, and undermine France's traditional role as a haven for the persecuted.

Sarkozy's own immigrant father might have failed to qualify for French nationality had his son's rules applied when he fled from Communist-controlled Hungary in the late 1940s, they say.

More than 5,000 people marched through Paris on Saturday to protest against the bill.

Further right

On the far right, Le Pen told a rally on Monday that the tougher line from Sarkozy and a far-right rival showed that his anti-immigrant views were gaining ground in France.

Many held up a map of France with the slogan "love it or leave it".

Le Pen's far-right rival Philippe de Villiers began his presidential campaign this month with blistering attacks on what he calls the Islamisation of France and a demand for an end to all mosque construction around the country.

Political analysts say Sarkozy is courting far-right voters after ensuring Paris climbed down last month over a labour law reform that caused mass protests that sometimes turned violent.

His presidential prospects could suffer if disillusioned voters switch to far-right parties as a result.

The bill comes as Chirac and Villepin, both badly mauled by the issue over the new law for young workers, are struggling to show they can still govern despite the setback.