Papua New Guinea's foreign minister has confirmed the release of one hostage but says he "cannot guarantee" the safety of at least three others held in the southern highlands.
At least four people, including an Australian-New Zealand archaeologist, were conducting fieldwork in a remote PNG region when they were captured by an armed group earlier this week.
Speaking on the sidelines of the Pacific Islands Forum in Nadi, Justin Tkatchenko said negotiations to see the group released continued.
"So far, so good," he told Australian Associated Press.
One hostage, who Mt Tkatchenko confirmed was a local woman and who the ABC reports was the program co-ordinator, has been released.
The archaeologist is a New Zealand national but Australian-based academic.
Mr Tkatchenko said a wide range of authorities in PNG were involved in negotiations to free the group.
"Our police force, our defence, our negotiators from the government side through the leadership of our minister for internal security," he said.
"It's a combined effort to look at the opportunistic situation by these people and see what their real intentions are.
"We don't at all support these kinds of activities and the full force of the law will go down on those that have carried out these acts that society does not tolerate."
While hopeful the talks would be fruitful, Mr Tkatchenko said he couldn't promise the hostages' release.
"I can't guarantee anything," he said.
Previously, the PNG government has said four people were taken captive however a statement from police suggested there might have been five.
Police Commissioner David Manning said he hoped to "secure the release of the other four" in a statement late on Thursday.
"We are offering the abductors a way out. They can release their captives and they will be treated fairly through the criminal justice system," he said.
"Failure to comply and resisting arrest could cost these criminals their lives."
The capture took place in the border region of the Southern Highlands, Hela and Western Provinces.
The ABC reports the hostages have been moved between villages in the area.
Their captors are asking for a ransom from the Australian and New Zealand governments.
