Interior minister Nicolas Sarkozy has ordered the expulsion of all foreigners convicted of taking part in the riots that have swept France for 13 nights.
Sarkozy said even foreigners with visas would be expelled if convicted
He told parliament 120 foreigners had been found guilty of involvement and would be deported without delay.
Police said overnight violence had fallen significantly - although trouble still flared in more than 100 towns.
The government has declared a state of emergency in Paris and more than 30 other areas to help quell the unrest.
The northern city of Amiens was the first to impose an overnight curfew under the new powers, which came into force at midnight.
The western towns of Rouen, Le Havre and Evreux and the French Riviera region have also said they will implement the measures.
KEY TOWNS UNDER EMERGENCY DECREE
However the Seine-Saint-Denis region north-east of Paris, where the trouble started almost two weeks ago, said it would not impose a curfew after violence diminished for a third night running.
Mr Sarkozy told MPs that non-French nationals - "not all of whom are here illegally" - had been convicted of taking part in the attacks.
"I have asked the prefects to deport them from our national territory without delay, including those who have a residency visa," he said.
Senior interior ministry official Claude Gueant said police had seen "a very significant drop" in the intensity of the unrest.
The number of cars set alight across France overnight Tuesday to Wednesday fell to 617, hundreds fewer than the night before.
Some 280 people were arrested and disturbances broke out in 116 areas, half the number affected the preceding night.
Cabinet can declare state of emergency in all or part of the country
Regional leaders given exceptional powers to apply curfew
Breach of curfew could mean two-month jail sentence
Police can carry out raids on suspected weapons stockpiles
Interior minister can issue house-arrest warrants for those deemed dangerous to public safety
Public meeting places can be closed down
House searches possible day or night
Authorities can control media, film and theatre performances
Emergency can only be extended beyond 12 days if approved by parliament
However, the authorities in Lyon said public transport would not run after 1800 GMT on Wednesday following a petrol bomb attack on Tuesday.
The areas covered by the emergency powers extend from the English Channel to the Mediterranean, including Paris suburbs and major cities such as Lille, Marseille and Toulouse.
The powers, which can be extended by parliament after 12 days, allow a state of emergency to be declared in defined areas, restricting the movement of people and vehicles.
Police are entitled to carry out house searches and ban public meetings.
Minors are subject to the law between 2200 and 0600 (2100 and 0500 GMT) unless accompanied by an adult, and are also banned from buying petrol.
Nearly three out of four French people support the powers, according to a poll published in the daily Le Parisien newspaper.
But some opposition parties, and the French magistrates association, have described them as a danger to civil liberties.
The far-right French politician Jean-Marie Le Pen told the BBC that rioters should have their French citizenship revoked.
The nightly protests have gripped deprived areas where unemployment is rife and residents complain of racism and discrimination.
The unrest was first sparked by the deaths in the run-down Paris suburb of Clichy-sous-Bois of two youths, who were accidentally electrocuted at an electricity sub-station.
The emergency powers handed to local authorities have been invoked under a 1955 law. This is the first time they have been implemented in mainland France.