One woman is dead and another in hiding after a brutal murder over alleged ''sorcery'' in Bougainville, Papua New Guinea police say.

Former primary teacher Helen Rumbali was beheaded last Thursday evening by a mob in Lopele village, southern Bougainville, after being accused of sorcery.

Another woman is in hiding in a nearby medical centre after she and Ms Rumbali were interrogated and tortured by their captors for more than 24 hours after being abducted from nearby Tandorima.

The mob accused the pair of using magic to kill another teacher.

Acting provincial police commander Paul Kamuai said his officers tried to intervene on Wednesday, but were confronted by a crowd armed with rifles and bush knives.