Celtic boss Neil Lennon claims his 'heart sank' when he saw a political banner display by the Green Brigade before Tuesday's UEFA Champions League defeat to AC Milan.
The vocal supporters' section of Parkhead displayed banners of hunger striker Bobby Sands and Scottish nationalist William Wallace surrounded by the words 'The terrorist or the dreamer, the savage or the brave, depends whose vote you're trying to catch or whose face your trying to save'.
UEFA, who have a zero tolerance on any display of political support at grounds, immediately opened disciplinary proceedings against the club for what it refers to as an 'illicit banner'.
The following day the SPFL followed suit claiming it would investigate a banner displayed by the Green Brigade during Celtic's 3-1 win over Aberdeen last Saturday.
The issue forced Peter Lawwell to condemn the supporters group and Lennon has backed the Celtic chief executive claiming 'political banners have no place at football grounds'.
"It is not guaranteed that we will play Champions League football every year so I went out early to take in the atmosphere at the ground," he said.
"But my heart sank when I saw it. It wasn't the time or the place for a display like that. It should have been a celebration rather than people having a grumble about something.
"When I came in here I tried to bring the club together again and I think we have done that, certainly with the performances over the last three or four years, so it is disappointing that some people want to bring cracks to the club.
"I don't know what we can do. It is not welcome within the stadium, we understand they may have legitimate complaints over some of the laws brought in but Celtic Park is not the place to display that.
"We are a football club at the end of the day, multi-cultural as well, so I think we need to put a stop to it."
Of the 3-0 defeat on Tuesday, Lennon hit back at criticism his team has received insisting they have been punching above their weight in recent years.
"What defines success for us in the Champions League?" he said. "We have only qualified for the last 16 three times in 14 years and a lot of managers had a lot more money than me and didn't do it.
"We have to be careful about throwing money at things. We have to make sure we have a club that can compete every year in the Champions League.
"If we can make the last 16, fantastic, but it takes a lot of money to do that. We have qualified and that was the most important thing.
"We will work to get better. We are in a transitional period. The team is not better because we lost Gary Hooper, Victor Wanyama and Kelvin Wilson in the summer.
"If you took Aguero, Yaya Toure and Vincent Kompany out of Man City's team would they be a better team for it? It is similar."
And Lennon is convinced this weekend's trip to Tynecastle affords his team the ideal chance to put their Champions League heartache behind them.
"We want to win it," he said. "We want to bounce back and the best thing the players can do is get back on to the pitch.
"There is a good atmosphere there and anything can happen on the day but I am expecting us to play very strongly and try to prevail."