In a letter sent to fans allocated tickets for Saturday's league match at Falkirk, the Parkhead club warned of the potential implications of stepping out of line.

Rangers supporters could face disciplinary action from the SPL after a minority of their fans were heard chanting sectarian slogans in last Saturday's match at Inverness.

Points could be deducted this season under new SPL regulations, and Celtic are determined to ensure their own fans behave to avoid any such sanction.

The letter explained: "We should not underestimate how serious this could be.

"Your support has earned the club worldwide recognition for its good nature and the passion with which you get behind the team, let's ensure that this is maintained this season."

It added: "We are a non-political and non-sectarian organisation and we ask in the strongest possible terms that you do not indulge nor encourage songs or chants or any other form of behaviour which could in any way bring the club into disrepute."

The club have warned they will take season-ticket passes away from any supporter who is identified as an offender, and issue indefinite bans from future matches.