Eight Amsterdam police officers have been left injured following a violent clash with Celtic supporters, according to reports.
The incident happened prior to Celtic’s 1-0 Champions League defeat to Ajax on Wednesday night and left officers with "had broken noses and needed stitches above their eyebrows and on their lips," a police statement said.
It added that "there were 15 arrests, mostly Celtic supporters. At the end of the afternoon, a large group of Celtic supporters attacked police officers in plain clothes. Eight were injured and one left unconscious."
Speaking to Sky Sports News, Amsterdam Police Inspector Rob Van Der Veen said: "39 people have been arrested and 27 of them are still in custody. We are dealing with them.
"I am not sure how many of them are Celtic supporters but there are a number of them, along with Ajax fans, in that group."
Van Der Veen went on to try and explain the reasons behind the altercation, adding: "At a certain moment there were around 1,500 Celtic fans on Dam Square.
"There were also police officers in riot gear and also police officers in plain clothes.
"At a certain moment a big group of the Celtic fans turned against the policemen in plain clothes and there was a big fight.
"This resulted in eight of our officers being injured, with broken noses, cuts to their faces, heads and lips. Some of the fans used bottles to hit the officers, which was not a nice sight."
On their return to Glasgow Airport a number of Celtic fans were asked for their version of events.
"Celtic fans were in the square having a drink and enjoying themselves. Obviously there was more there than had tickets for the game," a returning supporter said.
"The Dutch fans just attacked the Celtic fans, and when they asked police 'what is happening' the police started attacking Celtic fans, hitting them with batons while the Dutch fans were throwing bottles at them."
Another supporter said: "We were in the square just before it all kicked off and it was all the casuals who came into the squad trapping a lot of Celtic fans in the pubs and the security just wouldn't let them out."
The scenes on Wednesday followed a warning from Celtic to their supporters to be "extra vigilant" following a violent incident in a city-centre bar on Tuesday night.
It read: "Celtic Football Club is urging all supporters in Amsterdam for tonight's Uefa Champions League tie with Ajax to be extra vigilant following an unprovoked attack on Celtic fans last night.
"The attack in the city centre by an element of the Ajax support resulted in a number of arrests.
"Celtic are urging all supporters to be extra vigilant in the city centre and at the Amsterdam Arena."
Some 12,000 Celtic fans were expected in Amsterdam for Wednesday night’s match.