Roma have been warned by UEFA they could lose the hosting rights for next year's Champions League final if there is violence during tonight's quarterfinal clash with Manchester United.

Certain groups in Rome have a reputation for causing trouble and UEFA could move 2009's showpiece event if they feel the supporters won't be safe in the Eternal City.

"If tomorrow at Roma-Manchester United there are incidents outside the stadium as happened against Real Madrid, where people were stabbed, we will have to reconsider the decision to assign the Final to Rome," UEFA spokesman William Gaillard is quoted by the ANSA news agency.

Such a decision would also be a disheartening sign as Italy campaign to replace Ukraine and Poland as the host nation for Euro 2012.