UEFA have announced that Celtic are facing punishment after a section of supporters raised Palestine flags during Wednesday's Champions League win over Israeli champions Hapoel Be'er Sheva.
Disciplinary proceedings have been opened against the Scottish champions due to displaying an illicit banner under Article 16 (2) of the governing body's Disciplinary Regulations.
"Disciplinary proceedings have been opened following the UEFA Champions League play-offs, first leg, between Celtic FC and H. Beer-Sheva FC (5-2) played on 17 August in Glasgow (Scotland)," read a UEFA statement on Friday.
"Charges against Celtic FC: Illicit Banner - Art.16 (2) of the UEFA Disciplinary Regulations.
"This case will be dealt with by the UEFA Control, Ethics and Disciplinary BOdy on 22 September."
Possible punishments include a partial stadium closure or a ban on travelling supporters for European fixtures, as the Parkhead club have already faced sanctions on eight occasions in the last five years.