An Australian archaeologist and two Papua New Guinea researchers held for a week by 20 armed men in a remote part of the Pacific Island nation were released on Sunday, while their captors remain at large, a local official said.

Professor Bryce Barker and doctoral student Teppsy Beni from the University of Southern Queensland, and Papua New Guinea National Museum researcher Jemina Haro were released after a ransom payment, said Alphonse Seiyaka, an official with the government of Mount Bosavi, where the three were held in rugged terrain.

"They didn't catch the criminals," Seiyaka said. As soon as soldiers exchanged money for the Australian and the two Papua New Guinea women, he said, the captors "ran away into the bush."