Celtic are to be investigated by European football governing body UEFA following allegations of "illicit chanting".
UEFA said Monday the Scottish giants would be brought before their control and disciplinary body on December 8 to face a charge of an incident of an unsporting nature, namely illicit chanting, during the 3-1 Europa League victory over Rennes on November 3.
Celtic had already said they were looking into the claims which are understood to centre on songs supporting the Irish Republican Army (IRA).
A Celtic spokesman said Monday: "We have been made aware of this hearing in a letter from UEFA. We have not been given any detail on the nature of the alleged incidents and have not received any information on this matter directly from the police.
"Celtic supporters have a magnificent record of positive support for their team, something recognised by both UEFA and FIFA in recent years and we are extremely proud of this reputation.
"Therefore, the club will co-operate fully with any UEFA investigation."
The charge relates to UEFA disciplinary regulation 11.2, namely: "the use of gestures, words, objects or any other means to transmit any message that is not fit for a sports event, in particular if it is of a political, offensive or provocative nature".
Possible UEFA sanctions include a fine and ban on supporters, although Celtic could face a lesser punishment if found guilty as it would be deemed a first offence.
Celtic's Glasgow rivals, Rangers, have been punished on three occasions for "discriminatory" behaviour from their fans.
Celtic are a predominately Catholic club while Rangers fans are mainly Protestants. Both clubs have strong ties to the Ireland, where the largely Catholic IRA once waged a terror campaign in its quest for Irish unity.
The British controlled province of Northern Ireland is mainly Protestant while the Republic is largely Catholic.
Although sectarian hatreds have gradually been eroded within wider Scottish society down the years, they are still reflected within the country's football culture as evidenced by the hate campaign Celtic manager Neil Lennon, a Catholic, was subjected to last season.
A bill before the Scottish Parliament would create new offences relating to behaviour deemed to "incite religious, racial or other forms of hatred" both in and around football grounds and on the internet.
Those convicted could spend as long as five years in prison and be banned from football grounds.
Celtic 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.
Police announced they had launched an investigation into the "singing of sectarian songs" following the Scottish Premier League game on October 2.
Rangers fans were banned from travelling to their next away game in Europe and the club were fined more than Â£70,000 after being found guilty of two counts of "discriminatory behaviour" on the part of their fans in April following Europa League games against PSV Eindhoven.
The Ibrox club had received fines following previous incidents in matches against Villarreal and Osasuna.