Police in Papua New Guinea say they have arrested 29 people accused of being part of a cannibal cult and charged them with the murders of seven suspected witch doctors.

Madang Police Commander Anthony Wagambie confirmed on Friday a report in The National newspaper that cult members allegedly ate their victims' brains and made soup from penises.

He says the killers believed their victims were witch doctors who had been extorting money and demanding sex from poor jungle villagers for supernatural services.

Police reported that 28 men and women appeared in a Madang court on Tuesday charged with willful murder. It was not clear what happened to the 29th suspect. Murder is punishable by death in the poor South Pacific island nation.