Vandals set three buses ablaze near French cities overnight on the eve of the anniversary of riots that rocked France's multi-ethnic suburbs.
Masked assailants torched buses in the western Paris suburb of Nanterre and the eastern suburb of Bagnolet, but passengers fled before the flames engulfed the vehicles.
An empty, parked private coach was set on fire in Venissieux, a suburb of the eastern city of Lyon, and three youths ordered passengers off a bus in Athis Mons, south of Paris, and tried without success to set it on fire.
In the Bagnolet attack, one assailant held a pistol to the head of the driver while others forced passengers to get off.
Bus drivers refused to enter some of Paris's most troubled suburbs to protest against the latest attacks.
The attacks followed a daylight assault on a bus just south of Paris on Sunday. Youths on ethnically mixed estates around the capital have also staged several apparently concerted attacks on security forces in recent weeks.
"We cannot accept the unacceptable. . . . We refuse to see no-go zones created in our country," Prime Minister Dominique de Villepin said. "There will be arrests and immediate, exemplary punishment," he added.
Police say the violence has been building ahead of the October 27th anniversary of last year's riots.
Then, youths from mainly immigrant backgrounds burned cars and wrecked shops for three weeks in France's worst unrest for decades, blamed on poverty and discrimination.