Celtic face disciplinary action from Uefa over "illicit chanting" during the 3-1 Europa League win over Rennes at Parkhead earlier this month.
European football's governing body yesterday confirmed that Celtic will be called before its control and disciplinary panel on 8 December to face a charge of an incident of an unsporting nature, namely illicit chanting.
The Glasgow club had already announced they were "looking into the claims", which are believed to centre on songs about the IRA.
Celtic are understood to have been taken by surprise by Uefa's action, with club insiders suggesting that no issues were raised during or immediately after the match. It is thought that Strathclyde Police made the Uefa delegate aware of "offensive" singing during the encounter.
Possible Uefa sanctions include a fine and ban on supporters, although Celtic have not been punished for a similar offence before. The club last month urged fans to stop singing pro-IRA chants after being "inundated" with complaints from their own supporters following their 2-0 defeat by Hearts at Tynecastle.
Lothian and Borders Police announced they had launched an investigation into the "singing of sectarian songs" following that Scottish Premier League game on 2 October.
Rivals Rangers have been punished for similar offences in the past, with fans banned from travelling to their next game in Europe and the club fined some £70,000 for supporters' "discriminatory behaviour" in April after matches with PSV Eindhoven.