Celtic fans held Palestine flags aloft ahead of their Uefa Champions League match against Atletico Madrid on Wednesday night.
The build-up to the game, which ended in a 2-2 draw despite the hosts taking the lead twice, had been dominated by internal and external strife.
Thousands of Celtic fans defied the club’s guidance before kick-off by displaying Palestine flags, an act which is likely to lead to sanctions from Uefa, who has previously applied disciplinary action against the Scottish giants, including a £8,600 fine in 2016 for displaying Palestine flags in a game against Israeli side Hapoel Be’er Sheva.
Uefa’s Rule 16.2 states that club's are responsible for fan behaviour and disciplinary procedures may occur if a political message is displayed, with Barcelona and Celtic previously fined for showing national flags that Uefa deemed to have sent a political message.
Atletico’s decision to dispense with their striped shirts and wear an all-red top based on the one worn by the team that beat Celtic in the 1974 European Cup semi-finals also opened old wounds.
The Green Brigade, an ultra supporter group at Celtic Park, had previously said they would hand out flags ahead of the match, and the group has already been banned from away games after displaying the same flags at other recent matches, the BBC has reported.
The flags were also waved in other areas of the stadium not occupied by the Green Brigade.
Ahead of the fixture, the club announced the players and staff would wear black armbands as a show of respect for all those affected by the conflict and would make a contribution to the red cross.
But the club also asked that “banners, flags and symbols relating to the conflict and those countries involved in it are not displayed at Celtic Park at this time.”
The Green Brigade believes football fans have the right to express political beliefs.
Celtic fans have previously shown their support for Palestine, and in 2014 the club was fined after fans waved flags during a match against Iceland’s KR Reykjavik, and again during a 2016 qualifier against an Israeli team.
The Scottish club could also face being fined by Uefa for their actions on Wednesday night.
Celtic have an Israel winger, Liel Abada, who is currently out of the matchday squads with injury, but it adds another dimension to the actions of the fans.
The Independent has contacted Uefa for comment
Additional reporting from PA