Scottish champions Celtic have been fined €50,000 after "illicit" banners were displayed by fans during a Champions League match against AC Milan in Glasgow last month.

A group of fans, known as the Green Brigade, held up banners depicting IRA hunger striker Bobby Sands, who died in prison in 1981, and Scottish independence fighter William Wallace, prompting Uefa to implement disciplinary proceedings for the non-sporting nature of the banners.

“Clearly it is extremely disappointing that the club must pay another sizeable penalty following the actions of a small minority, particularly given the previous assurances which were made to the club and the widespread understanding of the likely outcome of such actions,” Celtic said in a statement on its website on Friday.

“Regrettably, due to previous charges being brought against the club, again following the actions of a small minority, the fines imposed by Uefa are increasing in scale. It goes without saying that such actions must stop now, before the club receives a competitive sanction or one which would affect our supporters attending European matches.”

Uefa’s code bans “the use of gestures, words, objects or any other means to transmit any message that is not fit for a sports event, particularly messages that are of a political, ideological, religious, offensive or provocative nature”.

Celtic were fined in 2011 over a banner display during a Europa League tie against Udinese, and were also sanctioned after supporters set off fireworks during a Champions League qualifier against Cliftonville earlier this season.