Two people were injured as violence erupted in Lille ahead of Germany's victory over Ukraine on Sunday.
Clashes broke out when German hooligans attacked Ukraine supporters close to the city's central railway station in the build-up to Germany's 2-0 win at the Stade Pierre Mauroy, German news agency SID reported.
SID quoted Volker Goll, who works for the state-financed Koordinatinstelle Fanprojekte (coordination centre fan projects), told SID that more than 50 German hooligans were involved.
"Police intervened very late," he added, with SID reporting that around 150 known hooligans had travelled to Lille.
A German TV reporter was attacked, and French police said two Ukraine fans were hurt after clashes on Place Charles de Gaulle.
Deutsche Hools drehen in Lille durch... Polizei: kaum vorhanden. #EURO2016 pic.twitter.com/71rcXAz5Hf
- Rafael Buschmann (@Rafanelli) June 12, 2016
Pictures and videos posted on social networks showed hooligans storming into a group of Ukraine fans, with chairs being thrown.
Other pictures showed far-right extremists posing in front of the Reichskriegsflagge, the German war flag used until 1919, giving Nazi salutes and reportedly chanting "Germany hooligans" and "we've marched in again."
Krawalle und fliegende Stühle in #Lille zwischen Deutschen und Ukrainern!#GERUKR #EURO2016 pic.twitter.com/C9jKac8SjX
- Manni1909 (@PartyPartybrder) June 12, 2016
According to a dpa report, German federal police stopped 18 hooligans from the city of Dresden and a further three from Kaiserslautern close to the French border on Sunday.
"Hooligans see this as their last chance to present themselves in public for many years," an unnamed, high-ranking German police officer told Spiegel Online.
"They want to go on a rampage, because they won't get the chance in upcoming years."
The officer added that the World Cups in Russia and Qatar in 2018 and 2022, as well as the pan-European 2020 European Championship, were difficult for hooligan groups because of high security, the threat of severe prison sentences and travel difficulties.