Fans of Russia's Fakel Voronezh and Ural Yekaterinburg were attacked in the stands during their FNL Cup tie in Cyprus.
Olympiacos hooligans attacked Bayern Munich fans during an Under-19 match between the two sides at the Greek club's training complex on Tuesday evening.
England fans clashed with riot cops in Prague on Friday evening ahead of the Three Lions’ Euro 2020 qualifier against the Czech Republic.
A hand grenade was found at a building used by ADO Den Haag fans on Tuesday morning.
Seven Newcastle United fans were arrested after a pitch invasion during Saturday's Premier League clash against Bournemouth at Dean Court.