Eight police officers were injured in a clash between football fans and officers before Celtic's Champions League match against Ajax in Amsterdam.
Amsterdam police said 15 fans were arrested after the incident in the city centre before kick-off yesterday.
The police force said fans armed with bottles and sticks attacked plain-clothed officers in an incident described as "coming out of nowhere".
One officer was knocked unconscious in the fighting in Dam Square.
Police said the majority of those arrested were Celtic fans, although it is believed that supporters from other clubs were also involved.
A police spokesman said: "At the end of the afternoon a large group of Celtic supporters attacked police officers in plain clothes.
"Eight were injured and one was knocked unconscious. A few of them had broken noses and needed stitches above their eyebrows and on their lips.
"Bottles and sticks were used in the attack which came out of nowhere. There were 15 arrests, mostly Celtic supporters."
Celtic lost the match 1-0 and face an uphill battle to reach the knockout stages of the competition.
Before the match Celtic urged fans in the city to be "extra vigilant" after a group of supporters were attacked in a city centre bar.
It was reported around 50 supporters were in the Old Sailor Cafe in the city when they were attacked by a group of masked men on Tuesday night.
There were no serious injuries and a number of people were arrested.
The attack follows trouble last month when a group of Ajax fans ripped up and threw seats at police and home fans as the teams played in Glasgow.
Uefa opened disciplinary proceedings against the Dutch club after the clashes with police and stewards at Parkhead during a match which the home side won 2-1.
A disciplinary case is to be heard on November 21.
The night before the match at Celtic Park, British Transport Police arrested two Dutch fans over alleged disorder in Glasgow Central train station.
Around 12,000 Celtic fans were expected in Holland for last night's match and the club said fans should not travel to the stadium unless they had a ticket for the Celtic section.
A club statement issued before the match said: "Celtic are urging all supporters to be extra vigilant in the city centre and at the Amsterdam ArenA, and to only stick to the advised areas for safety reasons."