Russia recognising Australian fighter Oscar Jenkins as a prisoner of war is a promising sign but won't guarantee a quick release, an expert warns.
An unverified video posted online shows the 32-year-old teacher from Melbourne wearing a military camouflage uniform and being asked by a captor to confirm he is alive.
"My name is Oscar Jenkins ... I come from Australia, I'm Australian," he says in a video uploaded to YouTube more than a week ago.
The identity of the man filming is unknown, but appears to be one of Mr Jenkins' captors who speaks to him in English.
The man says the date is January 17 but does not identify the location.
He says Mr Jenkins is a prisoner of war from the 66th mechanised brigade of the armed forces of Ukraine.
"Tell us about your health condition, about your mood. Are you OK?" he asks.
"I would like more freedom," Mr Jenkins says.
"I feel a bit weak. I've lost a lot of weight. I have a broken arm still, I think, and my hand is not good."
Mr Jenkins is wearing warm clothing and a beanie, as temperatures in Russia plunge to -15C.
The man filming says, "But you're alive" and then prompts the captured Australian to confirm that news of his death is wrong.
"Correct," Mr Jenkins says in response, before being told to remove his beanie.
"Everything is OK," the man filming says.
"He is alive and I think he will (be) better."
ANU Professor of International Law Donald Rothwell said the reported date in the video is significant, as it suggests the recording was prompted by earlier reports that Mr Jenkins was dead.
Russia has taken the view mercenaries do not have any entitlements, with confirmed reports of executions after their capture, he said.
"This is really the first time that we've got some reference by a captor that Jenkins might be and is being treated as a prisoner of war," Prof Rothwell said.
He said any suggestions the Australian could be released in a rapid or imminent prisoner exchange arrangement wasn't realistic.
"It doesn't reflect the way in which prisoners of war are treated," Prof Rothwell said.
"The best prospect for Oscar Jenkins at the moment is there being a resolution in a peace arrangement between Ukraine and Russia."
Ukrainian ambassador to Australia Vasyl Myroshnychenko previously said his government had added Mr Jenkins to its list of prisoners of war and would be negotiating for his release in an exchange.
Foreign Minister Penny Wong said the government was aware of the video in recent days.
"In relation to Mr Jenkins ... we should always be aware of Russia's propensity to provide us with incorrect information," she said.
The video wasn't part of initial evidence provided by Russia to confirm Mr Jenkins was alive.
Prime Minister Anthony Albanese said Australia has made representations to Ukraine, including a one-on-one discussion he had with Ukrainian President Volodymyr Zelenskiy.
"We still hold serious concerns for Mr Jenkins' welfare," he told ABC radio on Tuesday.
"We've made it clear to Russia that Mr Jenkins is a prisoner of war and that there are obligations that kick in in accordance with international humanitarian law, and they must be observed.
"We have called for Russia to release Mr Jenkins."
The Department of Foreign Affairs continues to provide support for his family.
It will be three years since Russia launched its invasion of Ukraine on February 24, 2022.
Opposition Leader Peter Dutton said Australia "stands proudly with President Zelenskiy and the Ukrainian people".
