Celtic are to be investigated by UEFA after supporters set off fireworks during Tuesday night's Champions League tie with Cliftonville at Parkhead.
Europe's ruling body confirmed that the Scottish champions have to answer a charge of breaching articles 16.2 of UEFA's disciplinary regulations.
Neil Lennon's side won the match 2-0 to reach to secure a 5-0 aggregate scoreline against the Irish side and set up a third qualifying round tie with Elfsborg of Sweden.
A Celtic club statement read: "Three fireworks were exploded within Section 111, causing the Match Referee to require a stadium announcement to be made instructing such behaviour to stop.
"As a result of this unprecedented step by a match official, Celtic FC will now be the subject of a disciplinary action for contravention of the UEFA Safety and Security Regulations."
Article 16.2 states that "all associations and clubs are liable for... inappropriate behaviour on the part of their supporters and may be subject to disciplinary measures and directives even if they can prove the absence of any negligence in relation to the organisation of the match" relating to, among other things, the "lighting of fireworks or any other objects".
Celtic were fined £21,000 by UEFA following a Europa League game against Udinese in Italy in December 2011 as a result of fans' misbehaviour.
On that occasion, the club were charged with "the displaying of a banner of an offensive nature and the setting off of fireworks by supporters".