France's Socialist opposition decided Tuesday to boycott a vote on a bill outlawing the full-face Islamic veil in protest at the sweeping ban that will apply to all public places.

Home to Europe's biggest Muslim minority, France is set to adopt a bill banning the wearing of the face-covering veil despite warnings from top legal experts that the move may be unconstitutional.

Socialist Party leader Martine Aubry told deputies at a meeting that while they should not vote against the bill, they should not take part in a vote scheduled for July 13, a Socialist party official told AFP.

"We are against the burqa but we believe that the means chosen to outlaw it are not good," said the party official.

The Socialist stance was agreed just hours before debate was to open at the National Assembly on the bill that would make it illegal for anyone to cover their faces.

The proposed law would impose fines of 150 euros (190 dollars) on those caught wearing the veil and up to 30,000 euros and a one-year jail term to men who force their wives or daughters to cover their faces.

President Nicolas Sarkozy's UMP party and its right-wing allies hold a strong majority in parliament and the bill could easily pass without support from the opposition Socialists.

But the government has made a point of seeking strong bi-partisan support for the legislation.

Debate on the burqa has raged in France for a year and Sarkozy has described the Muslim face coverings as degrading to women.

His critics however see the bill as a political ploy to pander to far-right voters by taking aim at a tiny minority of women who wear the full veil.

Fewer than 2,000 women wear the full-face veil in France, according to the interior ministry.

Justice Minister Michele Alliot-Marie, who will present the bill at the National Assembly later Tuesday, insisted the law was about upholding French values of secularism, gender equality and promoting integration.

"The law is not about the veil, but about deliberately covering the face in any way," she was quoted as saying by the daily Liberation.

"It is not a question of religion," she said. "The republic lives with its face uncovered."

The National Assembly lower house is set to hold a vote on July 13 following debate this week and the bill is expected to then go to the Senate in September.

Legal experts warn the broad scope of the law banning the veil in all public places instead of just in state institutions could be struck down by the constitutional court.

Similar laws are pending in Belgium and Spain, but the ban is particularly sensitive in France.

Muslim leaders fear it will stoke tensions by stigmatising France's estimated five to six million Muslims, many of whom live in volatile city suburbs.

To avoid tensions, the law would give police leeway to waive penalties and instead order offenders to enrol in a "citizenship course" to better understand French secularism.

No penalties will be applied in the first six months after its adoption.

French politicians have said the law will also apply to tourists from the Middle East and the Gulf who are often seen fully veiled in luxury shops on the Paris boulevards.