Italian Prime Minister Silvio Berlusconi has authorised the use of "drastic measures" in a crackdown on violence in Italy's football stadiums.
Berlusconi, who owns AC Milan, met Interior Minister Giuseppe Pisanu following the abandoned quarter-final second leg between Inter Milan and AC Milan after Inter fans showered the San Siro pitch with bottles and flares.
Berlusconi's office issued a statement saying: "There is a clear risk of even more serious incidents in future, a risk which must be avoided by all possible means.
"Premier Berlusconi urged the interior minister to maintain the firm line that has been taken for some time, with particular reference to preventative measures.
"However, resorting to the most drastic measures available should not be ruled out if necessary."
Tuesday's scenes were only the latest to shame Italian football and followed a warning this week from Pisanu that he might order high-risk matches to be played behind closed doors.
At the weekend, Lazio ultras - renowned for their far-right tendencies - brandished swastika flags and fascist banners during a Serie A game against Livorno and there was crowd trouble at several grounds across the country.
Tuesday's quarter-final second leg was the second Champions League game in Italy to be called off this season because of violence. AS Roma's match with Dynamo Kiev in September was stopped after referee Anders Frisk was struck by a missile.
Also in Italy Twenty Juventus fans were stopped by the police. We searched the vehicles, and their homes and we found baseball bats and other weapons. Eight of them have been detained by police for being in possession of arms."
Tensions are running high in Turin where extra police have been put on duty for tonight's match between Liverpool and Juventus following threats from groups of Italian ultras.