Celtic have warned fans of the prospect of "serious repercussions" for the club as they urged supporters to stop using pyrotechnics following their most recent UEFA charge.
Disciplinary proceedings have been opened against Celtic after the alleged setting off of fireworks in their Europa League Group E victory over Cluj last week.
The Parkhead club have already been fined £11,000 for fans using flares and throwing objects during the 4-1 Europa League play-off second-leg win over AIK in August.
The Scottish champions have called for such behaviour to stop and insisted they will bring in further measures to deal with it amid fears of "detrimental consequences" for the club.
A statement on Celtic's official website read: "Following the latest UEFA charge against the club for the use of fireworks at Celtic Park, it is with real disappointment and frustration that the club needs to appeal again for this behaviour to stop.
"UEFA's stance on the issue of pyrotechnics is unequivocal and very well-known.
"The club has been sanctioned on numerous occasions and yet, very disappointingly, this behaviour by a small minority persists.
"The serious safety concerns associated with such behaviour are obvious, as is the reputational damage which this behaviour and these charges have on the club. In addition, the numerous financial penalties placed on Celtic continue to come out the pockets of supporters who invest in the club.
"Celtic will be introducing further measures in order to deal with this behaviour. It has to stop.
"The club does not want it, our supporters do not want it and UEFA will continue to punish the club whenever it occurs as it is a clear breach of their regulations. It really is as simple as that.
"Given the number of repeated offences, we should also be very aware that there could be further, very serious repercussions which could have hugely detrimental consequences for the club and our supporters.
"It is hugely unfair that the enjoyment of Celtic matches could potentially be affected by the negative behaviour of a tiny minority."