Celtic midfielder Aiden McGeady has been fined two weeks' wages and suspended for the next two games for a breach of club discipline.
McGeady was reported to have clashed with manager Gordon Strachan following the 1-1 draw with Hearts on Saturday.
Celtic said in a statement: "Gordon's decision has the full support of the Celtic board of directors."
McGeady's agent David Holbrook said he was disappointed and told BBC Sport that the 22-year-old would appeal.
Reports claim that relations between the pair are at an all-time low after an argument in the dressing-room following Saturday's draw with Hearts.
Holbrook said: "I can confirm that Aiden has been fined by the club and suspended. He's shocked, disappointed and I can say he will be appealing.
"He feels that the action is completely unjustified."
McGeady's agent said he hoped the problems between the midfielder and Strachan could be resolved.
Holbrook said that the Republic of Ireland international would be disappointed to miss the Old Firm derby at Ibrox on 27 December.
"He wants to play in that game and every Celtic game," Holbrook added.
"He remains 110% Celtic; he's supported them and loves them.
"But there's a difference between how Aiden feels he's been treated by the club's hierarchy as opposed to his relationship with the club at large.
"He's as disappointed as the fans that he won't be turning out for the Old Firm game."
Holbrook would not be drawn on whether McGeady would now consider his long-term future at Celtic.
"Let's just say we intend to appeal the decision and see what the panel decides."
The return to Celtic from Aston Villa of Shaun Maloney has increased the competition for the wide berths with the Scottish champions this season.
Strachan has at times left McGeady, who has also been hampered by injury, out of his starting line-up.
Earlier in the week, Holbrook had denied knowledge of any bust-up between the pair.
News of McGeady's censure came on the same day Celtic completed the signing of winger Niall McGinn from Derry City for a fee in the region of £200,000.
McGinn, who was recently named the Eircom League young player of the year, made his Northern Ireland debut in last month's 2-0 defeat by Hungary.
The winger will officially join the Parkhead club on 1 January.
