The French premier on Tuesday announced tightened controls on immigration, part of his government's response to the country's worst civil unrest in four decades.

Authorities will increase enforcement of requirements that immigrants seeking 10-year residency permits or French citizenship master the French language and integrate into society, Dominique de Villepin said.

France also plans to crack down on fraudulent marriages that some immigrants use to acquire residency rights and launch a stricter screening process for foreign students, Villepin said.

Anti-racism groups widely opposed the measures, saying that greater government scrutiny of immigrants could stir up racism and racist acts.

Both Villepin and Interior Minister Nicolas Sarkozy have announced law-and-order measures since the rioting broke out this month in depressed suburbs where many immigrants live. The two �� both members of President Jacques Chirac's conservative party �� are expected to run for president in 2007, and both want to appear firm in response to the violence and France's broader social problems.

Marriages celebrated abroad between French people and foreigners will no longer be automatically recognized in France, Villepin said. Consulates must screen couples first before foreign partners can be granted French identity papers, he said.

"It's not an attempt to undermine the right to marry, but to check that all the conditions for a true marriage are in place," Villepin said, adding that the measure would be proposed to parliament in the first half of 2006.

The prime minister also said the government should have the ability to enforce a law outlawing polygamy. There are 8,000-15,000 polygamous families in France, according to official figures.

Some French officials cited polygamy as one reason that youths from underprivileged immigrant households joined the rioting �� a suggestion that outraged opposition politicians and human rights groups. They warned against fanning racism and anti-Muslim sentiment.

New restrictions on marriages would send the wrong signal, anti-racism activists said.

"This measure will make everyone suspicious of any marriage between a French citizen and a foreigner," said Assane Fall, of the anti-racism group SOS Racisme. "Does the government want to suppress the possibility of mixed marriages?"

The government's controls were "shortsighted" and could result in turning France against its immigrants, said Mouloud Aounit of anti-racist group MRAP.

The civil unrest broke out Oct. 27 near Paris and spread throughout France. While promising to ease unemployment for youths and fight racial discrimination, the conservative government also promised tighter controls on crime and immigration.

About 50,000 foreign students come to France each year to study. Foreign students will be screened in their home countries by centers run by officials from France's Education Ministry, Villepin said.

"We want to channel our efforts to receive the best students, the most motivated, those who have a high-level study project," he said.

The French president said two weeks ago that France also must be stricter in enforcing regulations that govern whether immigrants can move their spouses and children to France.

The government plans to propose a law next year covering legal immigrants who want to move their families to France. Villepin said immigrants should wait at least two years before they can apply, an increase from the current one year.

Source: CD/Agencies