French police Tuesday detained six suspected Basque separatists, Spanish media quoted Spanish police sources as saying, reported dpa.
The arrests were linked to an investigation into bars suspected of financing violent separatists in France.
The arrests were made in different locations in the French Basque region, according to Askatasuna, a group defending jailed activists of the militant Basque separatist group ETA in Spain and France.
The detainees were taken to a police station in Bayonne. Police searched several addresses.
One of the detainees was believed to belong to Batasuna, a party regarded as the political wing of ETA. Batasuna is banned in Spain but legal in France.
Some of the detainees had previously been sentenced for collaborating with ETA.
Over the weekend, police discovered an ETA camp north-east of Bordeaux, seizing documents and a hard disk, the French daily Sud Ouest reported.
ETA's campaign for Basque independence focuses on fighting the Spanish state, but the group has long had a part of its infrastructure based in France.