Police in Paris were filmed using tear gas on fans outside of the Stade de France ahead of Saturday's Champions League final.
A video posted on social media showed an officer spraying the substance towards fans through metal barriers.
In another video, spray was seen being blasted into the face of a young man who had been acting peacefully and seemingly complying with protocol.
It was claimed that children were within range when some of the spray was deployed elsewhere.
Indeed, footage showed a young child screaming for their mother, before police administered eye drops as treatment.
Kick-off between Liverpool and Real Madrid was supposed to be at 9.00pm local time but UEFA announced an initial delay of 15 minutes. The game did not begin until 9.36pm.
A message shown on the big screen inside the stadium claimed that the delay was due to "the late arrival of fans".
That message was later amended and replaced with one that blamed a "security issue".
But Jim Boardman, a journalist for The Mirror, tweeted that fans had been "waiting for HOURS to get into that stadium."
Commenting on reports that tear gas had been used, Boardman added: "It really is time football was run by fans instead of dinosaurs who treat fans like animals."
Oliver Holt, of The Mail on Sunday, also questioned UEFA's version of events.
Holt tweeted: "The narrative that UEFA are pushing about the late arrival of fans is misleading. Fans were here in plenty of time.
"It is the organization outside the stadium that's the problem. Reports of tear gas used outside now. A disgrace that fans - any fans - should be treated like this".
Andy Kelly, a journalist who was attending the event as a fan, was among those who were held outside the stadium.
He tweeted: "There's been zero communication with fans btw.
"No announcement about why we're still here. Why we've been tear gassed or even that the kickoff has been delayed. As abject an event as I've ever attended."
Former England striker Gary Lineker added: "I'm not sure it's possible to have a more poorly organized event if you tried. Absolutely shambolic and dangerous. @UEFA.com".
"It is the outer perimeter that is the problem," Olley explained. "It is a stadium that has main roads out of Paris and the river at the back and the issue is that there are underpasses where they have decided to check tickets.
"At that point they are checking tickets, searching bags and taking alcohol off people.
"The problem is it takes time but secondly there are a lot of people outside without tickets. In an ideal world you would want something to stop tens of thousands of people without tickets getting to the outer perimeter and chancing their arm. It is tense out there."
After the match, which Real Madrid won 1-0, UEFA released a statement.
It 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.
"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."
A Liverpool FC statement read: "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.
"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."