JAKARTA: Separatists in Indonesia's restive Papua region have released images that they say show a New Zealand pilot taken hostage last week is in good health, but pledged he would not be freed until authorities acknowledge the independence of the area.

The pilot, Philip Mehrtens, who flew a plane operated by airline Susi Air, was abducted by fighters from the West Papua National Liberation Army (TPNPB) last week after landing in the remote region of Nduga.

Reuters could not independently verify the authenticity of the images, but a friend of Mehrtens, who declined to be named because of the sensitivity of the issue, confirmed it was the pilot.

Sebby Sambom, a spokesman for the TPNPB, shared photographs and videos of a man wearing a jean jacket, surrounded by a group of about a dozen fighters, some armed with guns and bows.

"The Papuan military that has taken me captive to fight for Papuan independence, they ask for the Indonesian military to go home to Indonesia and if not, I will remain captive for my life," Mehrtens said at one point in the video.

One of the fighters is holding up the "Morning Star" flag, a symbol of Papuan independence.

In a statement accompanying the images, Sambom said that the pilot was in good health and that he was collateral in a political dispute.

Indonesia's chief security minister Mahfud MD vowed in a video late on Monday to ensure Mehrtens' release using "persuasive approaches, because the priority is his safety", but said could not rule out using "other ways", without elaborating.

"Taking civilians as hostage, for any reason, is unacceptable," he said.

A spokesperson for New Zealand's ministry of Foreign Affairs and Trade said they were aware of the photographs and video circulating but declined to comment further.

Indonesia's easternmost provinces have been wracked with a low-level battle for independence since the resource-rich region was controversially brought under Indonesian control in a vote overseen by the United Nations in 1969.

The conflict has escalated significantly since 2018, with pro-independence fighters mounting deadlier and more frequent attacks.