MEMBERS of an alleged cannibal cult, who police say are responsible for the deaths of seven people, have been arrested in Papua New Guinea.

The 29, including a 13-year-old boy and a teacher in his 50s, were arrested during a dawn raid at Biam village, Madang province on PNG's northeast coast last night.

Two men, one believed to be the group's leader and known only as "Joe", are still on the run.

Armed with home-made guns fashioned from rubber and believing they had supernatural powers to identify sorcerers, the group has killed four men and three women since April, police say.

"The last was last Thursday," Senior Constable Daniel Kapen, who led the raid, told AAP.

"The group alleges that there were some deaths related to sorcery in the area.

"They were initiated into a cultural house and believe they could identify sorcerers. It has been an ongoing problem."

Sorcery is legally defined in PNG.

The legal definition is between legal good magic, such as healing and fertility, and illegal black magic, held responsible for unexplained deaths.

However the government's Law Reform Commission is considering stamping out the law because of sorcery-related murders throughout the country.

Most cases of sorcery are also bogged down in the nation's beleaguered court system because most lack any real evidence.

Initial forensic reports and statements made by the accused led police to believe parts of the victims were eaten, however Mr Kapen declined to go into detail.

He also denied media reports the group was a cargo cult, a religious practice found in some pre-industrial tribal societies and formed around the belief wealth can be attained through magic.

"They were not demanding money off people," Mr Kapen said, adding that getting wealthy did not appear to be the motive for the murders.

"But we believe there was an exchange of money for the power to recognise sorcerers."

Villagers near Biam, a small village near Tangu sub station in Bogia district, were unable to vote in the national elections out of fear for their safety.

"Police will be following up on this matter as many were deprived of their constitutional rights to cast their votes because of this group," said Madang Superintendent Anthony Wagambie Jnr.

In 2010 cult leader Steven Tari, a self styled "Black Jesus", was found guilty of raping young "flower girls" who belonged to his sect.

Tari made international news when captured and arrested in March 2007 after eluding police for more than a year by moving from village to village or hiding in remote mountain camps in the Transgogol area of Madang province.

At the time he had thousands of village followers, including a core of armed warriors to protect him.