Australia's government is deeply disappointed Chinese-Australian writer and former diplomat Yang Hengjun has been moved to criminal detention in China.
The government has confirmed his transfer but is still seeking clarification over the reasons for his detention.
"If he is being detained for his political views, then he should be released," Foreign Minister Marise Payne said in a statement on Friday.
The former diplomat with China's ministry of foreign affairs who became a pro-democracy campaigner was being held in Guangzhou after arriving from the US in January.
The 53-year-old, who has held Australian citizenship since 2002 and has a doctorate from the University of Technology Sydney, was living in New York as a visiting scholar at Columbia University.
Australian officials have visited Dr Yang in detention six times, most recently on June 27.
But Senator Payne said despite writing twice to her Chinese counterpart asking for a fair and transparent resolution and for Dr Yang to be allowed to see his lawyers, that had not happened.
"We have worked tirelessly and in good faith with the Chinese government to advocate for Dr Yang's interests since he was detained," she said.
"We expect basic standards of justice and procedural fairness to be met."
Friends and family of Dr Yang expect him to be charged with endangering state security.
His Australian lawyer Rob Stary said a political intervention was the only likely means by which to resolve the issue.
"We're certainly calling on the foreign minister to exert whatever pressure she can upon the Chinese authorities," he told AAP.
"Australia has a special relationship, obviously, with China and so hopefully there can be some bilateral discussions about how it is that Dr Yang can be released.
"I don't have any unrealistic expectation though just at this stage, particularly bearing in mind they say he's engaged in some sort of internal security breach."
Labor backed Senator Payne's statement and called on China to treat Dr Yang in a fair, unbiased and transparent manner.
Human Rights Watch has urged the government to "vigorously press" for Dr Yang's release.
"We are concerned that Yang was held for six months in 'residential surveillance in a designated location' or RSDL and as such may have been subjected to torture, mistreatment and coerced confessions," the organisation's Australia director Elaine Pearson said on Friday.
Dr Yang's wife, Yuan Xiaoliang, who is a permanent resident of Australia, has been banned from leaving China.
Mr Stary said he was worried about the implications of Dr Yang's move to criminal detention on Mrs Yuan, and noted the Australian government's statement did not mention her.
Ms Pearson said China had no legal basis for preventing Mrs Yuan's departure.
"The Australian government should redouble efforts to press Chinese authorities to allow her to leave," she said.