Australian Prime Minister Anthony Albanese warned Moscow on Wednesday that if reports of one Melbourne man being killed after being captured by Russian forces on a Ukrainian battlefield are true, the country will take the "strongest action possible."

“We’ll await the facts to come out, but if there has been any harm caused to Oscar Jenkins, that’s absolutely reprehensible and the Australian government will take the strongest action possible,” the prime minister told reporters on Wednesday.

The remarks come as officials work to confirm reports that Jenkins was killed in Ukraine, with Foreign Minister Penny Wong earlier on Wednesday warning that Russia's ambassador in Canberra could be expelled if the Australian was harmed.

"I want to be clear: all options are on the table," she told ABC Radio National on Wednesday.

Last month, a social media video post revealed that Jenkins, 32, had been arrested by Russian forces in Kramatorsk, in the Donbas region of eastern Ukraine.

A video of a man identifying himself as Oscar Jenkins and saying that he is a biology teacher who lives in both Australia and Ukraine was posted on Russian social media platforms.

Citing sources inside Ukraine, local Australian broadcaster Seven News had reported Tuesday that Jenkins, an Australian volunteer soldier fighting on behalf of Kyiv, is "believed to have been killed after being captured by Russian forces on the frontline."

In a related development, the Russian ambassador to Canberra was summoned to the Foreign Ministry to clarify the reports and reiterate Australia's expectations that Russia will follow international law, according to Seven News, citing authorities.

"The Russian Federation is obligated to treat all prisoners of war in accordance with international humanitarian law," the Foreign Ministry said, noting that the ministry is still providing consular support to Jenkins' family during this difficult time.

At least seven Australians have died fighting Russian forces on behalf of Ukraine.