The Catholic Church in Queensland is warning followers of the cult, Magnificat Meal Movement, to leave the group as police fear cult members may be preparing for a mass suicide.
The priest at Helidon, west of Brisbane, Father John Ryan, says police will use the church hall as a command post for next month's operation which has all emergency services on alert.
There is concern over reports that cult leader Debra Geileskey has claimed she and her followers will die in a fire on September 9.
Father Ryan says his advice is for followers to leave.
"I wouldn't say that it's likely to happen but I would certainly say this - that the ingredients for tragedy are there," Father Ryan said.
"Wherever people have a leader who has what would appear to me to be blind allegiance from a group of people who might well do anything she demanded, well there are the ingredients," he said.
Father Ryan says the movement is not part of the Catholic Church.
"I do not believe it is a genuinely spiritual movement and I think lots of good people are trapped in there and deluded," he said.
"I just say [to them] what I've always said and that is get out.
"Come back to the real church and if you belong to the Catholic Church, as just about all of them do, come back to the real church and find the freedom there," he said.
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