Shambolic scenes outside the Stade de France saw supporters with tickets made to wait in huge queues until after the match began.
The Reds lost to Real Madrid at the Stade de France, just north of the city, on Saturday evening.
However, shambolic scenes outside the ground saw supporters with tickets made to wait in huge queues until after the match began.
Fans affected by the situation said police officers used pepper-spray “unprovoked” while they were waiting to get in.
Uefa said the delay was caused by the late arrival of Liverpool fans, but the club said that was “totally inaccurate”.
A Merseyside Police spokesperson said on Twitter: “MERPOL was deployed to this evening’s match.
“Can only describe it as the worst European match I’ve ever worked or experienced.
“I thought the behaviour of the fans at the turnstiles was exemplary in shocking circumstances.
“You were not late 100%.”
Fans swore at armed police officers in the area as they left, saying their tactics led to the mayhem.
Prefecture de Police, the Parisian police force, said in a statement queues formed after fans arrived without tickets.
It continued: “Exerting strong pressure to enter the enclosure, these supporters delayed access to spectators with tickets.
“Taking advantage of this action, a number of people managed to cross the gates protecting the stadium enclosure.
“The rapid intervention of the police allowed the return to calm and the evacuation of the disturbers outside the forecourt of the Stade de France.
“The dispersal of the spectators takes place without difficulty. No major incident was observed in the two fan zones.”
One supporter could be heard saying he was left waiting outside for four hours with a ticket due to the delays.
Speaking after the game, supporter Robbie, 24, said: “I got pepper-sprayed, the first time that’s ever happened to me.
“It was unprovoked, people were just standing there waving at the police to let us in, we had tickets.
“Police were just spraying us for no reason, even kids and older people, it was bad.”
He said fans had not been acting inappropriately at the time.
Some Liverpool fans could be seen arguing with Real Madrid supporters and locals outside the stadium after the match.
Footage on social media appeared to show people climbing over barriers as crowds built up, and the kick-off was delayed by more than 30 minutes.
Police carrying shields and riot gear had moved into the area shortly after 8pm.
Supporters showed what appeared to be tickets to officers after a gate was closed, denying them entry.
Bottles were thrown at the officers who responded with tear gas, leaving some fans holding their eyes.
Supporters still waiting to get in were visibly frustrated.
One fan, Carl Noades, 63, told the PA news agency: “There only seems to be one gate open, it’s ridiculous, the game’s kicked off and we’re stuck outside.
“It’s a disgrace, the way they’re treating us is shocking, there’s no organisation.”
Tensions outside the stadium were then driven by young Parisians.
Liverpool supporters said hundreds of locals were taunting riot police, causing gates to be shut.
One fan said: “This will be pinned on us, but it’s nothing to do with us.
“There’s hundreds here causing trouble, they’re not even for the game – it’s chaos.”
Supporters were arguing with ticket officials on the other side of the fence, and beyond the gates some people, a few wearing Liverpool shirts, were taken away.
Other fans flocked to a nearby pub to watch the game.
Nick Smith, 42, told PA: “I had a ticket, paid through the nose, especially at the minute when everyone’s struggling.
“But complete lack of organisation means I’m at a pub and not where I should be.”
Liverpool fans with tickets were later let into the stadium hours after queuing up and well after the match began.
Officers used tear gas, batons and shields to force young locals away from the area outside.
One man was wrapped in a blanket surrounded by emergency workers after being caught up in a scuffle.
Scores of supporters with legitimate tickets were then allowed to enter.
One fan told PA: “I’ve queued up for four hours, my wife and I have tickets. Appalling.
“I’m devastated, Liverpool fans should not get the blame for this.”
A Uefa statement read: “In the lead-up to the game, the turnstiles at the Liverpool end became blocked by thousands fans who had purchased fake tickets which did not work in the turnstiles.
“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.”
Liverpool later released a statement calling for a thorough investigation into events outside the ground.
A club spokesperson said: “We are hugely disappointed at the stadium entry issues and breakdown of the security perimeter that Liverpool fans faced this evening at the Stade de France.
“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.”