Three Spanish "ultras" fans were arrested in the southern city of Nice for carrying neo-Nazi banners and another three for trying to bring flares into the stadium ahead of Spain's Euro 2016 match against Turkey, regional police said on Friday.
French authorities have been cracking down on more radical fan groups after clashes in Marseille last week marred the start of the month-long European Championsip soccer tournament.
Tournament organiser UEFA has also imposed a strict ban on all flares entering stadiums, although at several games fans have managed to get them inside.
Defending European champions Spain booked their place in the last 16 round of Euro 2016 with a convincing 3-0 win against Turkey in Nice.
Vicente del Bosque's men bossed the Group D tie from the kickoff, with a double by Juventus' Alvaro Morata and a first competitive international goal from Nolito sealing a comfortable win.