Two new suspects have been detained in the investigation into the Bastille Day attack in Nice in which more than 80 people were killed.
The Paris prosecutor's office said on Tuesday that two men have been in custody in southern France since Monday.
It gave no details about why they had been arrested.
Five people have already been jailed on preliminary terrorism charges linked to the July 14 truck rampage by Tunisian driver Mohamed Lahouaiej Bouhlel, accused of helping him obtain a pistol and other support.
The so-called 'Islamic State' group claimed responsibility for the massacre on the Promenade des Anglais.
French authorities say 31-year-old Bouhlel was inspired by the extremist group's propaganda, but have uncovered no evidence that 'IS' orchestrated the attack.
The new arrests come amid political scandal over limited police presence in Nice on the night of the bloodshed.