Celtic will not appeal against the fine imposed by UEFA for "illicit chanting" at last month's Europa League tie against Rennes at Celtic Park.
UEFA's control and disciplinary panel yesterday imposed a fine of 15,000 euros (£12,700) for chanting at the 3-1 win over Rennes on November 3.
The match delegate was informed of pro-IRA chanting by the Strathclyde police match commander.
Celtic chief executive Peter Lawwell told his club's official website, www.celticfc.net, today: "The heavy fine imposed by UEFA is an indication of the seriousness with which it treats such matters.
"We would reiterate our own position that, however small a minority is involved, such chanting is not welcome at Celtic Football Club.
"Clearly, it is very disappointing and a source of real regret amongst our supporters that Celtic's proud history of exemplary conduct has been tarnished in this way by such a tiny minority.
"However, this is a clear warning that such behaviour will not be tolerated and together, Celtic Football Club and our supporters will do all we can to ensure that this incident is not repeated.
"We would like to thank our supporters for their magnificent conduct since the match against Rennes. We are proud of the fantastic and positive reputation we have established across Europe over many years, and the club and our fans will be doing all we can to ensure that this is protected."
Earlier this month, Celtic escaped Scottish Premier League action over pro-IRA chanting, the league ruling the club had taken all reasonable action to prevent such "unacceptable conduct", which was reported by police following a goalless draw against Hibernian on October 29.
UEFA have been more willing to punish clubs and national associations in similar instances.
The European governing body have fined Rangers for "discriminatory" behaviour on three occasions, the latest offences also prompting a one-match travel ban on supporters.