"But that's not consistent with what our government claims to be a values-based foreign policy, and surely a critical value here is [that] we look after the interests of Australian citizens."
His case has been highlighted again after Yang Hengjun's wife - who is a permanent resident of Australia - was banned from leaving China.
Australian-Chinese writer Yang Hengjun charged with espionage
Mr Jennings says the federal government's approach also sends a signal to Australian citizens, particularly those with Chinese ethnicity, that they may not get the protection from the Australian government that they might expect.
"Frankly what we have is a Chinese state that will put any ethnic Chinese, regardless of their citizenship, into custody if it suits them to do so. And I think it's very unwise of the Australian to react to that in a low-key way. That's not how Australian citizens of any ethnic background should expect the government will look after them if they are overseas."
'Time to escalate the matter'
Elaine Pearson from Human Rights Watch said she holds similar concerns about the treatment of Australians abroad.
"It sends a terrible signal to other Australians who may have been critical of the Chinese government in the past that an Australian citizen can be used effectively as a hostage in this way," Ms Pearson said.
Human Rights Watch wrote a letter to the Foreign Affairs Department last month where they called for the immediate release of Mr Yang.
"The Department of Foreign Affairs' quiet diplomacy approach clearly hasn't been paying off," Ms Pearson said.
"Six months later, Mr Yang is still in secret detention, he has had no access to a lawyer, it's clearly time for the Department of Foreign Affairs to escalate."
No formal charges laid after almost six months in detention
Australian citizen Yang Hengjun, 53, has been detained in China since January this year.
He has been held in "residential surveillance", which can go on for six months without a formal charge being laid.
Lawyers for Mr Yang say urgent and strong intervention by the federal government is required after Mr Yang's wife was blocked at the airport from leaving China to return to Australia by state security forces on Thursday.
On Sunday, his wife Yuan Rui Juan was questioned by Chinese authorities after unsuccessfully trying to leave the country.
It is understood she is subject to an exit ban but was not detained.
Mr Yang's wife, Yuan Rui Juan was forcibly taken away by officers from the Ministry of State Security on Sunday, and interrogated for two hours, according to her lawyers.
A close friend of the couple - Professor Chongyi Feng - who has had regular contact with Ms Yuan fears that China's secret police are seeking to hold her as a hostage in China in order to gain leverage in their interrogations of her husband.
"They continue to attempt to extract a false confession from him," he said.
"If they cannot get Mr Yang to confess to political crimes, they hope to force her to confess something against her husband."
Dr Feng said Ms Yuan is living in constant fear.
"She is worried the secret police can take her away at any time and feels helpless," he said.
"She doesn't know what to do next."
Australia has asked for clarification: Payne
Mr Yang's lawyers are demanding Foreign Affairs Minister Marise Payne apply for his immediate release.
"They are Australians, and every fellow Australian - and our government - should demand their immediate release," Mr Yang's lawyer Robert Stary said.
"It is not a crime to engage in free speech or advocate for democratic rights.
"But this is all Mr Yang has done.”
On Monday, Ms Payne said Australia had been regularly raising Mr Yang's case with China at senior levels.
"We have requested his case be treated fairly, transparently, and expeditiously," Senator Payne said.
The minister said the Australian continued to have consular access and asked that Mr Yang be granted immediate access to his lawyers.
"Australia has asked for clarification regarding the reasons for his detention," Minister Payne said.
"And we have said that if he is being detained purely for his political views then he should be released."
Mr Yang's lawyers are also urging the government to extend consular assistance to Mr Yang's wife, who was granted permanent residency in Australia two months ago.
"It is concerning that an arbitrary line, in terms of consular assistance, has been drawn between husband and wife, based on Yuan's citizenship status alone," the lawyers said.
Dr Feng says the Australian government has been "very soft" in trying to assist Mr Yang's case.
"They have told me that all levels of representation have been used to Chinese authorities but I don't know what kind of demands they have put forward," Dr Feng said.
"So far they haven't publicly asked for Yang's release.
"That is not on the table but I believe it is a legitimate demand."
Mr Yang continues to be held in isolation. His only contact with the outside world is monthly visits from the Australian consulate.
Dr Feng said Mr Yang has not been well.
"They still torture him. Three guards will take shifts 24 hours a day watching over him," Dr Feng said.
"They will leave a bright light on 24 hours a day. He has a small stool he sits on for 12 hours a day and he is not permitted to go outside at all."