A China Foreign Ministry spokeswoman refused to comment on the matter saying, "we don't have the information, send inquiries to the related department".

John Garnaut, the former journalist and adviser to Prime Minister Malcolm Turnbull, who is a friend of Mr Yang, hoped the matter would be resolved quickly.

"Let's hope he reappears today and we can all agree there's just been a misunderstanding. Nobody wants an Australian Michael Kovrig," he said in reference to the former Canadian diplomat being held in China.

Mr Kovrig and another Canadian, Michael Spavor, are being held on suspicion of "harming national security", a phrase often used by Beijing when alleging espionage.

Canberra and other allies have condemned the detentions. Any move to hold an Australian citizen on similar charges would be a major escalation of tensions, which have flared since Canada arrested Huawei executive Meng Wenzhou in early December.

Unless Mr Yang is released overnight his detention is set to dominate Mr Pyne's one-day visit to Beijing, which was designed to mend ties after a difficult 12 months for the bilateral relationship.

"The government is committed to maintaining a long-term constructive relationship with China, founded on shared interests and mutual respect," Mr Pyne said prior to leaving.


He is set to meet China's Minister for National Defence, General Wei Fenghe, and other senior officials during the visit, which will also take in Japan and Singapore.

"I warned him it was dangerous, given what happened to the Canadians," said UTS academic Feng Chongyi, a friend of Mr Yang's. Steven Siewert

The diplomatic tension with China stems from Australia being at the forefront of international efforts to ban Chinese telecommunications equipment maker, Huawei, from 5G mobile networks.

Australia's subsequent ban, which was been followed by New Zealand, has angered Beijing as Huawei was deemed a national security threat.

Canberra also called out China's cyber hacking late last year, an area over which it has previously declined to apportion blame.

In recent years Mr Yang has been a visiting scholar at Columbia University in New York, where he has been only mildly critical of China's Communist Party.

Professor Feng said while his friend was a supporter of democracy he had never identified as a "dissident".

Mr Yang had, however, called out Chinese political interference in Australia more than a decade ago, when Beijing mobilised students to defend the Olympic torch relay against protesters.


Professor Feng said Mr Yang had returned to China from New York with his wife, Yuan Rui Juan, and her daughter while they waited for an Australian visa.

The family arrived in the southern city of Guangzhou on the morning of January 20, where Professor Feng believes they were picked up by MSS agents.

The family was scheduled to fly to Shanghai a few hours after landing but never boarded the flight.

Mr Yang's wife made it to Shanghai later in the day where she left her daughter with family, before boarding a flight to Beijing.

"I have been told by contacts in China that he is in the hands of the Ministry of State Security in Beijing," said Professor Feng.

"If he was able to negotiate his release it would have happened by now. The only option is to get the Australian government involved."

In a statement the Department of Foreign Affairs and Trade said it was "seeking information about an Australian citizen who has been reported missing in China".

"Owing to our privacy obligations we will not provide further comment," the Department said on Wednesday.