Celtic have been fined 25,000 euros (approx £21,000) for fans' misbehaviour in the Europa League game against Udinese in Italy last December, UEFA have confirmed.
After the 1-1 draw at the Stadio Friuli, the Parkhead club were charged with, "the displaying of a banner of an offensive nature and the setting off of fireworks by supporters".
The decision to fine Celtic was made by UEFA's control and disciplinary body on February 23.
A UEFA spokesperson told Press Association Sport: "Celtic have been fined 25,000 euros by UEFA's control and disciplinary body for breaching Article 11 of the UEFA disciplinary regulations.
"The decision was taken on February 23. It is nothing out of the ordinary that it wasn't announced then. We can have 100 cases at the monthly meetings. Celtic did not appeal."
Some Celtic fans held aloft a two-part banner which insulted UEFA, days after the club were fined about £12,700 for "illicit chanting" involving pro-IRA songs at a Europa League game against Rennes at Celtic Park.
Several flares were also let off and one was thrown on to the pitchside track.
Celtic banned for life one fan who was arrested in Italy over the alleged assault of a club steward, and who they say was one of those responsible for the banner.
Manager Neil Lennon and chief executive Peter Lawwell hit out out at the "rogue" element within their support on the day after the game.
The club also vowed to sift through photographic evidence to find those fans responsible for the use of the flares, warning that they will take "appropriate action".
Lawwell said: "It is very frustrating. Those people are not Celtic supporters.
"We will weed them out and these guys will not get back into Celtic Football Club.
"One or two silly little juvenile boys doing funny kids' pranks and stuff is bringing the whole of Scottish football down."
Lennon added: "My only surprise is that they got the spelling (on the banner) right.
"I am very disappointed, they have let me down, they have let the board, players and background staff down and 99.9% of the support down."
Article 11 pertains to: inappropriate behaviour on the part of their supporters, including; the invasion or attempted invasion of the field of play; the throwing of objects; the lighting of fireworks or any other objects; the use of laser pointers or similar electronic devices; 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; acts of damage; any other lack of order or discipline observed inside or around the stadium."