St Pat's boss Tim Clancy says the officials must take "appropriate action" if there are racist incidents in tonight's Europa Conference League clash in Sofia.
Having banked €750,000 for reaching the third qualifying round, the Saints face a difficult away first leg tie against CSKA in Bulgaria (6pm Irish time) with a further €1m on the line.
The Saints can expect to face a hostile atmosphere. Alan Pardew quit as the Bulgarian club's boss in June after his own players were racially abused.