By Mario Cacciottolo
The violence between fans of Manchester United and AS Roma has brought the shadow of football hooliganism sharply back into focus.
Dr Stott says police were only deployed amongst United fans
The fighting which broke out before and during the Champions League match at the Stadio Olimpico in Rome is a throwback to the dark days where what went on in the stands often overshadowed the events on the pitch.
Questions have been raised over the tactics and behaviour of the police in quelling the violence, and one of the critics is
psychologist Dr Clifford Stott, of the University of Liverpool.
He is an expert on football hooliganism and crowd dynamics and has previously advised the Home Office.
Dr Stott attended Wednesday's match in Rome to observe the crowd and said the Italian police had failed to control the situation, or even themselves.
"I saw senior police officers trying to restrain their own men and failing to do so," he said.
"They only had police on the Manchester United side and just stewards on the Roma side. So when the trouble began they could do nothing at all with the Roma fans.
"I saw one United fan walking away and a policeman go up to him and hit him over the head."
Dr Stott said that, in his opinion, the initial provocation came from the Roma fans.
"I arrived with the United fans two hours before the game started and the Roma fans were throwing missiles for that time. They carried on doing so during the match as well.
"Eventually the United fans began throwing missiles back over which inflamed the situation.
"And when Paul Scholes was sent off for Manchester United there was a surge by both fans towards the clear fence that was keeping them apart. The police then deployed straight away."
Dr Stott said that the entire incident could possibly have been avoided if the Roma fans had been policed properly.
"The question is whether if the initial missile throwing by Roma fans had been stopped, whether the United fans would have begun reacting and if the police would have had to come in at all," he said.
"There were three factors at play here - the Manchester United fans, the Roma fans and the police.
"The relationship between these groups can lead to the dynamics that lead to a riot.
"One issue that has to be addressed is the behaviour of Roma fans in the stadium. If they had behaved that way in England they would have received a club ban and faced a criminal prosecution.
He said that the police were deployed next to Manchester United fans and so could not react to things happening elsewhere.
But at a police press conference on Thursday, the chief of policing in Rome Achille Serra said he supported what his force had done.
"To criticise the police is a sport," he said "The British always like to do it.
"The police were forced to intervene between two sets of violent fans and once you are in the middle of that you have to go in strong."
Mr Serra also said he had not seen any cases of police brutality but if evidence was produced he would investigate immediately.