Australia Is "urgently seeking clarification" on reports that a citizen has been detained in North Korea, the government said on Thursday after his family reported that he had not been in contact.
Alek Sigley's family said they had no confirmation that the 29-year-old Pyongyang university student had been detained.
"Alek has not been in digital contact with friends and family since Tuesday morning Australian time, which is unusual for him," a family statement said.
Attorney-General Christian Porter, who is based in Mr Sigley's hometown of Perth, told Perth Radio 6PR: "This particular jurisdiction, most Australians' common sense would tell them, makes this a matter of the utmost seriousness."
The Department of Foreign Affairs and Trade said it was providing consular assistance to the family but did not confirm the man's identity.
"The department is urgently seeking clarification. Owing to our privacy obligations, we will not provide further comment," a department statement said.
Australia does not have an embassy in North Korea. Finance Minister Mathias Cormann, who is also based in Perth, said Australia's embassy in South Korea "has reached out to relevant officials in North Korea".
"There is obviously some complications in providing consular assistance into North Korea," Mr Cormann told reporters in Japan. "We work through the Swedish government in North Korea and all of these steps are under way."
Mr Sigley was studying Korean literature at Kim Il-sung University and ran guided tours through a travel company he founded, Tongil Tours, according to his posts on social media.
He told the Australian Broadcasting Corporation two years ago that he wanted to break down negative stereotypes about the country.
"If we thought it was unsafe, we would stop doing these tours," Mr Sigley said. "We wouldn't be able to bear the moral and legal responsibility of bringing people to North Korea if it was dangerous."
Official media in North Korea have not mentioned the reported arrest.
Mr Sigley's family described him as an Asian scholar and traveller who had visited, studied and lived in several countries.
He speaks Korean and Mandarin fluently as well as some Japanese, the family said.
He has travelled to North Korea several times since 2014, the statement said.
Mr Sigley posted on social media pictures of his marriage to his Japanese wife Yuka in Pyongyang in May 2018. His family said his wife lives in Japan.
South Korean television station Channel A cited an unidentified source in reporting the arrest but the source told the network it was not immediately clear why Mr Sigley had been detained.
In March this year, Mr Sigley wrote for Guardian Australia about living in North Korea, saying that as a long-term foreign resident on a student visa he had "nearly unprecedented access to Pyongyang".
"I'm free to wander around the city, without anyone accompanying me," he wrote. "Interaction with locals can be limited at times, but I can shop and dine almost anywhere I want."
Australian National University in Canberra confirmed Mr Sigley had graduated there last year with a bachelor's degree in Asian studies.
"On behalf of the ANU community, I extend my concern and thoughts for his well-being, as well as to his family, his friends and colleagues," Vice Chancellor Keith Nugent said. "We hope for a speedy and positive resolution to his reported situation."
