Tear gas was used by French police as supporters were held in tightly packed areas around the Stade de France, causing safety fears to spread among those who were there.
“This is the greatest match in European football and supporters should not have to experience the scenes we have witnessed tonight.
“We have officially requested a formal investigation into the causes of these unacceptable issues.”
European football’s governing body, UEFA, said the issue was caused by people without valid tickets trying to enter the stadium and that tear gas was used to maintain control.
“This created a build-up of fans trying to get in. As a result, the kick off was delayed by 35 minutes to allow as many fans as possible with genuine tickets to gain access.
“As numbers outside the stadium continued to build up after kick off, the police dispersed them with tear gas and forced them away from the stadium.
“UEFA is sympathetic to those affected by these events and will further review these matters urgently together with the French police and authorities, and with the French Football Federation.”
Photos showed fans crammed into fenced areas after a bottleneck formed around a particularly tight entry point at the Liverpool end.
Many fans with tickets say they were held back from entering the stadium in dangerously crowded areas and that communication from security was poor.
“People without tickets forced the barriers and tried to get inside the stadium to watch the match,” a spokesperson for the Paris Police Prefecture told CNN. “These attempts created crowd movements.”
As confusion spread ahead of kickoff, videos emerged on social media of people — with no clear affiliation to a team — scaling fences around the stadium and running into the ground.
The match eventually started but there were many empty seats at the Liverpool end of the stadium.
Merseyside Police, who attended the game in an observatory and advisory capacity, said “the vast majority of fans behaved in an exemplary manner, arriving at turnstiles early and queuing as directed.”
“We know that people would have witnessed a lot of distressing scenes last night and we wish everyone returning home from Paris on a safe journey.
“Our focus today will be supporting Liverpool city council with the policing of the homecoming parade.”
After the match, Liverpool manager Jurgen Klopp says the team was aware of the pre-match incidents and that their families were impacted.
“I couldn’t speak to my family yet, but I know the families had real struggles to get into the stadium,” he said.
“I heard a few things that were not good, it was obviously pretty tricky out there but I don’t know more about it.”