Papua New Guinea police are hunting the leader of a sex cult that promised villagers a bumper banana harvest if they engaged in public sex.

The alert was raised after a villager from Yamina in Morobe province walked 12 hours to the nearest town to report the cult's activities.

He told police the cult's leader and his followers have been using threats of violence to force people to have sex in public for the past four months.

The Post Courier reports villagers had been promised their banana harvest would increase every time they fornicated publicly.

Three police officers trekked into the village over the weekend but the leader, identified as Thomas Peli, was able to escape into the bush.

Police reinforcements are being sent to the area.