Supporters of the rival teams clashed outside the Stadio Olimpico before the game which finished 1-1.

"It's difficult to give a comment on what has happened," said Spalletti.

After watching a video replay of the ugly scenes, Spalletti added: "These people are sick."

The trouble marked the second consecutive game between Roma and Manchester United in the Italian capital which has been marred by violence.

Moreover, it has added to a difficult year for Italian football. A Lazio fan was recently shot and killed by a police officer, an incident that is still under

investigation.

That death led to fan unrest in Bergamo and outside the Italian Olympic Committee (CONI) headquarters in Rome.

Earlier this year, a policeman died during riots outside the Catania stadium prior to a Sicilian derby.

Despite the troubles, Roma's match with Manchester United did go ahead.

Spalletti was not satisfied with the outcome of the game, despite Roma preventing Sir Alex Ferguson's club from becoming the fifth team to win all six games in the Champions League group stages.

Alessandro Mancini's 71st minute goal cancelled out Gerard Pique's first-half opener but Roma could have still clinched the win had Mirko Vucinic's strike shortly after not struck the post.

"We deserved to win this game considering what we did in the second half," said Spalletti.

"Both teams were cautious in the first half but we did well after the re-start.

"We had many opportunities to score but we were unlucky.

"Mancini has scored a beautiful goal and he proved today that he can change the outcome of a game."