Six people were arrested in the Paris region on Monday as part of a raid on a suspected radical Islamist cell allegedly planning "terrorist acts" on French soil, a source close to the investigation told AFP.

The suspects, aged between 22 and 38, were "all known to police for serious delinquency" and are being detained by the police anti-terrorist unit in the Paris suburb of Levallois.

The members of the suspected Islamist cell include one man from Benin, another from the Comoros and four French nationals, a source close to the case said.

They are suspected of being involved in the hold-up of a branch of the Banque Postale in Seine-et-Marne in April "and were apparently planning to commit other armed robberies," the source close to the investigation said.

According to the anti-terror police investigators, "they were planning to commit terrorist acts targeting well-known figures in France," the source added.

The suspects can be held for up to 96 hours before being charged or released.