Uefa have threatened to move the 2009 Champions League final from Rome's Stadio Olimpico if Manchester United fans are targeted in the Italian capital tomorrow night.

Ten United fans were stabbed last season when the club played Roma, and there was more trouble when Real Madrid visited last month.

Previously, three Middlesbrough fans were stabbed in 2006 and there have been numerous incidents involving knife-wielding gangs outside the stadium before domestic matches.

Uefa communications director William Gaillard said they were serious about moving the final if there was more trouble.

Gaillard said: "The situation inside the stadium has improved dramatically and we hope it will go well tomorrow and there are no reasons to expect problems inside the stadium.

"But we cannot afford to organise the final of the Champions League in a city where people are getting knifed every game. We will be watching and we are serious that if we have incidents like when Manchester United visited last year or Real Madrid last month, then we would have to reconsider our decision for the 2009 final."

He added: "We cannot have responsibility for bringing 40,000 people to the final and risk them being knifed in the city. We will be watching closely tomorrow and the rest of the season and next season. The police have to do their job.

"It's a fantastic venue and a beautiful city, and we realise these people have nothing to do with football, but if fans are afraid and it's dangerous we will have to look at the whole matter."

United have issued detailed advice for fans and warned them to use official free shuttle buses rather than travel independently on public transport.