In Papua New Guinea (PNG), several researchers, including local academics and an Australian professor, have been kidnapped under threat of violence.
According to media reports, the group was on a study trip when they were taken hostage by armed men in a remote highland area.
According to officials, a ransom has been demanded for their release.
The hostages should be released "alive and safe," according to PNG Prime Minister James Marape, who says authorities are in contact with the abductors.
The initial capture of a larger group resulted in the release of some local guides, according to reports.
Although the exact number of those still detained is unknown, Australian news organizations estimate that there are four or five. They include academics and students from PNG as well as an archaeologist from an Australian university.
Reporters were informed by Mr. Marape that PNG authorities had spoken with the Australian who had confirmed the group's survival.
He claimed that authorities and the kidnappers were having "running conversations" and that the military and the police were ready to help.
But first, he added, "we want those criminals to free those who are being held in captivity.".
"There is nowhere to flee and nowhere to hide. ".
Mr. Marape said the situation had been kept "under close wraps because of the sensitivity" but did not specify when the group had been taken.
However, he made an effort to reassure the hostages' families, saying: "I'm confident, I'm optimistic, and I'm praying that we get them out. ".
The Department of Foreign Affairs and Trade of Australia has not yet responded.
In the nearby Indonesian province of Papua, separatist fighters earlier this month kidnapped a New Zealand pilot.