[LILLE, France] French police moved onto the streets of Lille to keep order on Wednesday as tens of thousands of Russian, English, Welsh and Slovak fans arrived for the latest round of high-risk Euro 2016 football matches.
Authorities fear that Russia's game against Slovakia on Wednesday followed by a key England-Wales clash in the nearby city of Lens on Thursday could trigger a new bout of street fighting.
A police spokesman said seven arrests were made during the night, mainly to stop fights erupting between rival groups of fans.
They included two Russians held over tensions in a cafe where chairs and bottles were hurled and two Ukrainians accused of carrying prohibited weapons, the spokesman said.
"There were three cases of brawls between small groups starting between midnight and 1 am but these were quickly broken up."
Pitched battles erupted on the streets of Marseille on Saturday between Russian and English fans, the worst violence at an international football tournament since the 1998 World Cup.
Violence also flared in the stadium following their 1-1 draw, prompting UEFA to warn Russia it would be thrown out of the European Championship finals if there was more trouble.
French authorities said 4,000 police and gendarmes would be on duty in Lille to prevent a repeat of the unrest which saw 35 people injured. Ten people, including six England fans, have been sentenced to prison terms over the Marseille battles.
British authorities have also sent extra police to France to help in the operation.
French authorities have said they expect between 40,000 and 50,000 England and Wales fans and 15,000 Russians to gather in Lille with a smaller number of Slovak supporters.
Bars in Lille city centre shut at midnight on Tuesday and will do so again before the England game. Sales of alcohol in supermarkets have also been restricted.
But the tension was evident as rival groups gathered in bars, with a handful of Russian fans briefly throwing chairs and bottles at England fans who were chanting taunts.
"If the English are brave enough to come, we'll crush them. We hate the English," one Russian supporter told AFP.
But another Russian fan, Stanislav, said: "We are here for the game, not for the conflict."
French authorities also rounded up a group of more than 40 Russian supporters in a hotel near Marseille on Tuesday.
Alexander Shprygin, a far-right figure who is head of a Russian football supporters' club, said he was part of the group.
Marseille prosecutors believe they have enough proof to charge some of them over the unrest in the Mediterranean port city.
French prosecutors have said 150 Russian supporters who were "extremely well-prepared" and "extremely violent" evaded arrest in Marseille.
Europe's governing body found Russia responsible for the Marseille stadium disorder at the weekend and ordered the "suspended disqualification" of the team.
It also fined the Russian Football Union 150,000 euros (S$229,356).
Russia's Sports Minister Vitaly Mutko said Moscow accepted the UEFA ruling but called it "excessive".
England captain Wayne Rooney and manager Roy Hodgson have made a public appeal to the country's fans to avoid violence.
Russian striker Artem Dzyuba said however he was frustrated at the portrayal of England supporters "like angels" in the confrontations.
UEFA has also warned England it could be disqualified if there is more trouble, but only Russia was charged over the conduct of its fans.
The huge security operation around the tournament was originally aimed at neutralising the threat of jihadist attacks just seven months after 130 people were killed in a wave of shootings and suicide bombings in Paris.
The murder on Monday of a police officer and his partner in a Paris suburb by a radical claiming allegiance to the Islamic State group has also raised tensions.