More than 30 Manchester United fans were arrested in the Belgian city of Bruges when fights broke out after United's 4-0 Champions League victory over Club Brugge on Wednesday.
Dirk van Nuffel, the city's chief constable, said glasses and chairs were thrown in a clash between English and Belgian "hooligans."
Trouble flared when around 30 Belgian thugs attacked United fans in the Charlie Rockets pub after the game, which United won easily to seal a 7-1 aggregate success.
Fighting then spilled out into the street, where missiles were thrown.
Van Nuffel said 32 travelling fans and six Belgians had been arrested near the bar.
"They were all registered and then released. We have the identities of all the people involved," he added. "We will pass those identities to the British police and they will decide whether to charge them.
"Glasses and chairs were thrown, but there was no major damage."
One policeman suffered injuries in the incident, Van Nuffel said.
Greater Manchester police officers flown in to look out for any trouble reported that one United fan had been detained for resisting arrest and another for damaging a police car.
Van Nuffel said 25 more United fans had been arrested near the stadium for not having a ticket, with all released soon afterwards.
But he added: "My general impression of the Manchester United fans was very good, especially the ones at the match.
"They drank a lot, but that is an English tradition. On the whole I was very satisfied with them."