Two men from Rome have been arrested on suspicion of attempted murder after a man was left in a critical condition when he was attacked before Liverpool’s Champions League semi-final match against Roma on Tuesday evening, police have said.

Police and paramedics were called to the Albert pub, next to the Kop end of Liverpool’s Anfield stadium, shortly before the first leg match kicked off, where they found the victim, believed to be a 53-year-old man from Ireland, who had suffered a head injury.

Merseyside police said the men arrested were aged 25 and 26 and one of them was apprehended inside the ground. They were among nine men, aged between 20 and 43 years, arrested on suspicion of various offences, including affray, actual bodily harm and possession of offensive weapons, among others.

Officers appealed for witnesses of the incident in which the 53-year-old was injured to come forward. They said forensic examination had been carried out at the scene and CCTV footage from the area would be reviewed. DI Paul Speight said police believed the victim was in Liverpool with his brother for the match.

“Witnesses report that the victim was hit with a belt and then fell to the ground. Paramedics treated him at the scene and he was taken by ambulance to Walton Neurological Centre, where he is being treated for a head injury. His condition is currently described as critical and his next of kin have been informed.

“The place where this incident occurred is right by the ground and was heaving with fans making their way to the game. I would appeal to anyone who has any information, or mobile phone footage of the incident to contact us urgently, as information they have could be vital to our investigation.”

Such video footage does appear to exist, with clips posted to Twitter showing clashes between supporters with ambulances in attendance, and suggestions that a group of Roma fans had used belts as weapons.

In a statement released on Tuesday night, Liverpool FC said it was “shocked and appalled” by the incident. “Our thoughts, in the first instance, are with the victim and his family at this very traumatic time. We will be offering them our full support. The club has been liaising with the emergency services since the incident occurred and will continue to do so.”

There was an increased police presence around the stadium after Manchester City’s team bus had its windows smashed by bottles and cans prior to the quarter-final earlier this month.

The team arrivals passed with no repeat of that trouble, but there were plenty of red flares – despite specific requests from the authorities not to bring pyrotechnics. Liverpool fans were even pictured waving flares from the roof of a police van, though with no apparent aggression. Officers said they were investigating whether any offences had been committed.

Before the match, Ch Supt Dave Charnock of Merseyside police had appealed for calm, saying: “We know that this will be a busy operation and we hope that fans attending the match will act as ambassadors for their clubs and enjoy what I am sure will be a good game.”