At least 64 people were killed in tribal fighting in the northern highlands of Papua New Guinea, local police said on Monday.

They were killed in what is believed to have been an armed early morning ambush near the town of Wabag, 600 kilometers northwest of the capital, Port Moresby.

Assistant Commissioner of Police Samson Kua said the toll is likely to rise further.

"We believe there are still some bodies are still out there in the bush," he said.

The exact circumstances of the deaths were not immediately clear, but police said there had been reports of heavy gunfire in the area.

The incident is thought to be linked to a conflict between Sikin and Kaekin tribesmen.

(With input from AFP)