MANCHESTER, England (AFP) -- Police and fans clashed briefly outside Manchester United's Old Trafford football ground Tuesday, ahead of a tense Champions League tie with AS Roma.

Up to 100 people were involved in a brief flare-up shortly before kickoff of the quarterfinal second leg tie, although a Greater Manchester Police spokesman told AFP there had been only "a minor disturbance between a small number of people".

The force added that there had been "a number of arrests" in the skirmishes, which lasted up to five minutes, but could not provide exact figures.

Witnesses said that Manchester United fans had tried to rile Italian ones but the police intervened swiftly to prevent trouble.

Television pictures showed officers circling crowds with batons and dogs as well as some missiles being thrown at police. Fans were later shown being escorted into the ground just over an hour before the match started.

At last week's clash in Rome, several United fans needed hospital treatment after being stabbed before the match and Italian police baton-charged the visiting supporters during the first half.

Some 3,800 Italian fans arrived on 14 planes Tuesday and there was no trouble in downtown Manchester.