Twenty West Ham fans will appear in an Italian court following their arrest after clashes with rival supporters in Italy.
More than a dozen people were injured before the UEFA Cup match with Palermo.
Six English people, six police officers and five locals suffered minor injuries in fighting in Sicily.
Tension was already high after T-shirts bearing the slogan "The Mafia" - a reference to Sicily's links with the Italian criminal underworld - were sold outside West Ham's ground ahead of the first leg earlier this month, which the London club lost 1-0.
Supporters were left disappointed after West Ham lost 3-0.
Trouble flared just before midnight the night before the match and continued for more than an hour as rival groups threw bottles and chairs in the city's Teatro Massimo district.
Palermo police spokesman Virgilio Alberelli said 500 people were involved in the brawl, and when officers tried to break it up they also came under attack.
Some 20 Britons and a local were arrested for violence against public officials, while 109 other West Ham fans were stopped, identified and released. It took police in riot gear more than an hour to bring the violence under control.
More than 2,500 West Ham fans travelled to Palermo for the game.
Authorities in Britain are expected to seek banning orders against any fans found to have caused trouble.
