Scottish club Celtic have reportedly been fined £21,000 because of their fans' inappropriate behaviour during a Europa League clash against Italian club Udinese at the Stadio Friuli in Italy in December, according to a Guardian report.

UEFA has charged Celtic with "the displaying of a banner of an offensive nature and the setting off of fireworks by supporters" following the Scottish club's 1-1 draw with Udinese.

UEFA's control and disciplinary body, who have been doing a lot of disciplining, of late, after numerous cases of racial abuse and fans' misbehaving, came up with their decision on 23 February, after Celtic failed to appeal.

"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," Daily Mail quoted a UEFA spokesperson as saying.

Meanwhile, Celtic, who have vowed to take action against those responsible for creating a negative atmosphere, have banned another fan who was arrested for allegedly assaulting a club steward, for life.

"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," the Daily Mail quoted Celtic manager Neil Lennon as saying.

"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 per cent of the support down," added Celtic's chief executive, Peter Lawwell.

The Scottish club had earlier been slapped with a £12,700 fine following similar misbehaviour at Celtic Park during another Europa League tie against Rennes. However, instead of learning from their mistakes, the fans went on and insulted UEFA.