Celtic's elimination from the Champions League by AC Milan is likely to be compounded by a Uefa charge over a Bobby Sands banner.
The Green Brigade supporters displayed a banner of Sands alongside Scottish warrior William Wallace, in an effort to highlight the supposed hypocrisy of the Scottish government, which has jailed Celtic fans for singing Republican songs in commemoration of Sands.
Sands, who led and died in the Irish Republican Army's 1981 hunger strike, is considered a freedom fighter by a portion of Celtic's Catholic fanbase but is regarded as a terrorist by the Scottish authorities.
Celtic chief executive Peter Lawwell branded the Green Brigade's well choreographed statement as "nothing more than clear disrespect for the club and our supporters".
However, in a statement, the Green Brigade defended the banner and argued the Scottish Government legislates "expressions of Irish identity, culture and politics" illegal.
"Given that it is Celtic fans who are filling up prison cells and court rooms because of the Offensive Behaviour at Football Act, and the manner in which it criminalises legitimate expression of political opinion, this display could not have been more relevant in the current context," the statement added.
"While we understand and sympathise fully with fans who may disagree with the timing of the display we are honest enough to admit that the timing was of no coincidence. This act has been in place for over 18 months yet the club have offered next to no support to the fans on this matter.
"As a group, we were told that Celtic Football Club would publicly support the fans on this issue.
"Regrettably, this has not transpired in spite of the fact that public pressure could have had a telling impact on the justice committee as they discussed the possibility of an early review of the act.
"It is our opinion that the level of apathy from Celtic PLC towards the criminalisation of their supporters is unforgivable.
"We find their accusation of the Green Brigade disrespecting the club to be completely ironic and totally laughable when we consider the level of disrespect they have repeatedly shown to their supporters for far too long."