European football's governing body announced an initial 15-minute delay before Sunday's (AEST) showpiece at Stade de France, which Real Madrid went on to win 1-0, citing "security reasons" for the hold-up in fans entering the stadium.
Both sides had already completed their warm-ups by the time kick-off was first delayed and had made their way back to the dressing rooms in Paris.
The two teams returned for a second warm-up at 21:05 local time before the match finally started at 21:36 – 36 minutes later than planned – after a second delay.
British broadcaster BT Sport reported Liverpool fans had complained of heavy-handed policing outside the stadium, suggesting tear gas had been used on supporters.
Liverpool has since released a statement on the matter, requesting an investigation into the events.
"We are hugely disappointed at the stadium entry issues and breakdown of the security perimeter that Liverpool fans faced this evening at Stade de France," the statement read.
"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."
UEFA later blamed the use of fake tickets for the hold-up in supporters' entries, promising to review the situation alongside local authorities.
"In the lead-up to the game, the turnstiles at the Liverpool end became blocked by thousands of fans who had purchased fake tickets which did not work in the turnstiles," a UEFA statement read.
"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."