PARIS (Reuters) - French police questioned four men and a woman on Tuesday after an anti-terrorism operation in the northern town of Rouen and two other parts of France, a judiciary source said.

During a search near Rouen, police took away two handguns and two rifles, the source said, though police added that the weapons were legally held.

The police operation was undertaken as part of a preliminary investigation launched in Paris into the possibility that terrorist acts were being planned, the source said.

France has been hit by a series of Islamist militant attacks in Paris and elsewhere in the past two years which have killed more than 230 people. Security has been stepped up across France ahead of the final vote of its presidential election on May 7.