Irish Premiership club Linfield have been fined 15,000 euro for breaching Uefa regulations which prohibit standing during a Europa League tie.
The sanction relates to the Belfast side's home game against Swedes AIK Solna at Mourneview Park on 17 July.
The club say the punishment is now under review by their legal advisors.
"This promises to have serious ramifications both for the club at large and for the team budget during the season ahead," read a statement.
"The fine relates to Linfield supporters watching the game from a standing position behind the goal, an action specifically prohibited by Uefa.
"It is with considerable frustration that no sooner has the new season started than the Club's Board of Directors are faced with another difficult disciplinary issue involving our own supporters.
"This is particularly annoying to the club as extensive efforts were made on the day of the game to avoid this specific issue arising, including an article on our club website and repeated announcements over the stadium PA system.
"Those individuals standing behind the goal were also approached by Linfield FC stewards, the Club secretary and Club Health and Safety Officer.
|Statement issued by Linfield FC on their club website|
|"Our supporters must realise that Linfield does not operate in a vacuum where we are not bound by the rules and regulations that all other clubs in European competition are subject to"|
"When the problem was further highlighted to Linfield officials by the Uefa Match Delegate, a number of Linfield Directors also approached the supporters standing at the start of the second half of the game and were not just ignored, but were exposed to personal abuse for their trouble.
"Linfield appeal to all genuine supporters of the Club to attempt to work with us on this and other similar issues."
In May, the south Belfast club was fined £1,200 by the IFA over the singing of sectarian songs by a section of the club's supporters during a league game at Coleraine in March.
The Blues had successfully challenged a previous fine of £3,250 in relation to the singing of sectarian songs during a County Antrim Shield semi-final against Cliftonville as the IFA's own Appeals Board had not followed the proper procedures.
"Our supporters must realise that Linfield does not operate in a vacuum where we are not bound by the rules and regulations that all other clubs in European competition are subject to," continued the statement.
"Similarly, Linfield are also bound by the rules and regulations of local football and supporters will be only too aware of the difficulties we have faced over the last couple of seasons.
"It is particularly disappointing to the Board of Directors that several of the individuals who continued to stand behind the goal despite the advice and warning given have been identified as long-standing supporters of the Club and even include Club Members."
"Given the severity of the probable punishment in this case, Linfield must reserve the right to issue sanctions against any supporters identified as having been involved in any of the issues outlined or in any future incident which gives rise to financial sanctions against the club."