Insult was added to injury last night as Italian football authorities joined Rome police in condoning the terrifying scenes in the Olympic Stadium on Wednesday, with fears that Manchester United will be punished by Uefa for the ugly incidents even though the club believe that their fans were innocent victims.

Eighteen United supporters and two Roma fans required medical attention for injuries sustained during their Champions League quarter-final first leg and in a prematch ambush by the Italian club’s notorious “Ultra” supporters, which resulted in several stab wounds.

United expressed serious concern in a statement yesterday, citing “indiscriminate beatings” by the local Carabinieri and promising their assistance with a Government investigation into the disturbances. But club officials were shocked and disturbed to hear comments from the Italian football federation (IFF) and the Rome police, who claimed that the actions of their force were justified.

Uefa, European football’s governing body, has launched its own investigation, with United likely to be charged for the “improper conduct” of their supporters, just as they were in the match against Lille, staged in Lens, in the previous round.

United were fined £6,300 and could face more serious sanctions this time, although their participation in the Champions League is not thought to be under threat.

The reaction in Britain, not for the first time in recent years, has been one of outrage at the heavy-handed approach of Rome police, but in the Italian capital — to United’s immense displeasure — the Carabinieri have been widely praised for their tactics.

“The English press speak of heavy-handed police but we owe gratitude to our law enforcers and I don’t believe those who try to make games safe can be crucified in this manner,” Giancarlo Abete, the IFF president, said.

Achille Serra, the Prefect of Rome, said: “To criticise the police is a sport and the British always like to do this. The police were forced to intervene between two sets of violent fans and once you are in the middle of it you have to go in strong. In my opinion the police’s performance was correct.

“If you can show me evidence of police brutality then I will of course look into it, but as far as I’m concerned, there is no evidence of this. It did not seem like a night of violence to me. There were incidents before and during the game, but nothing that I would say was serious.”

Serra’s comments met with outrage in Manchester. “This happens time and time again to football supporters travelling in Europe,” a spokeswoman for the Independent Manchester United Supporters’ Association said. “Football supporters — and not just from United — get treated terribly everywhere we go and Uefa need to look into this very carefully because, the way things are going, it’s only a matter of time before there’s a very serious incident. These comments from the Italian authorities don’t so much disgust me as confirm everything I already thought about the police in some countries.”

Although much of the United fans’ displeasure is directed at the Italian police, there is also anger about a seemingly organised attack on 300 supporters by Roma’s “Ultras” on a bridge over the River Tiber before the match. There are also fears that a minority of United supporters may attempt to exact revenge against the 3,500 Roma fans travelling to Manchester for the second leg on Tuesday.

Greater Manchester Police intend to increase the number of officers inside and outside Old Trafford to deter clashes. A spokesman said: “GMP is experienced at policing large-scale football games. We will have adequate resources to police the area in and around the ground, in the city centre and on Salford Quays. Officers from our tactical aid unit, dog unit, mounted unit and traffic sections will be utilised alongside an increased presence of patrolling officers.”