The Interior Ministry cited 'absolute urgency' for the expulsion of the 20, who were among 26 who had been held at a former military barracks north-east of Paris. The authorities began detaining militants on 4 August, after five Frenchmen working for their embassy in Algiers were murdered.
The Foreign Minister of Burkino Faso said his country had accepted the Algerians as a humanitarian gesture, but that they were not expected to stay there more than three days. Their final destination has not been disclosed.
France's three consulates in Algeria, in the cities of Algiers, Annaba and Oran, were discreetly closed at the beginning of this week, making it impossible to obtain French visas in the former North African colony.
The Foreign Ministry announced that a new centralised visa service was being set up in the Breton city of Nantes to vet all applications. Officials said only 'recommended' Algerians would receive permission to enter France.
Police said two arms caches used by supporters of the banned Algerian Islamic Salvation Front (FIS) had been uncovered, at Clichy in the northern Paris suburbs and at Aix-en-Provence in southern France.
Charles Pasqua, the Gaullist Interior Minister, said after the weekly cabinet meeting that he hoped the expulsions would 'serve as a lesson to those who don't respect the laws of the Republic and also those of hospitality'.
Mr Pasqua, announcing the original detentions a month ago, said that, while the militants would not be sent to Algeria, where they would face prison at least, they would be forced to leave France once another country could be found to take them.
They were reported to have been taken from their detention centre early yesterday. Their lawyers said they had not been informed of the expulsion procedure, carried out under a 1945 law allowing for foreigners to be expelled without a court hearing if their departure was deemed to be 'an imperious necessity for state security or public safety'. The Interior Ministry said the 20 had been involved 'in activities likely to present a danger to the safety of our compatriots'.
At the same time as the militants were detained, Mr Pasqua ordered police to carry out spot checks of immigrants to weed out FIS sympathisers, a measure still in operation, which has led to extra and highly visible police patrols in the main cities.
Only a few Islamic militants have been found this way, but the operation has permitted police to detain many more immigrants for other irregularities. Criticised by human rights organisations, the police checks have been popular with the public at large.
The six detainees who were not expelled from France were under house arrest, the Interior Ministry said.Reuse content