Canberra is demanding transparency and fairness in the treatment of an Australian citizen being held in "residential surveillance" in Beijing.
China says it is holding Chinese-Australian writer Yang Hengjun on a charge of "engaging in criminal activities endangering China's national security."
Foreign Ministry spokeswoman Hua Chunying offered no further details in making the comments about Mr Yang at a daily news briefing in Beijing on Thursday.
Defence Minister Christopher Pyne, who is in Beijing for security talks, raised Mr Yang's detention with Chinese Defence General Wei Fenghe.
"During discussions with General Wei, (the minister) raised the issue of the detention of Mr Yang; that he be treated fairly and transparently; and that he be accorded consular assistance, without delay," Mr Pyne's spokeswoman said in a statement.
"General Wei assured (the minister) that, while he was not personally aware of the case, Mr Yang would be treated well and that the general would seek further information."
Mr Pyne earlier told reporters the Australian government is "concerned with the residential surveillance of Mr Yang", likening the writer's situation to home detention rather than jail.
Australian embassy officials had an initial meeting with Chinese officials in Beijing on Thursday afternoon to discuss Mr Yang's detention.
He has not yet been granted access to consular assistance.
An Australia-China consular agreement requires either government be told within three days if one of their citizens is detained.
Chinese authorities took four days before alerting Canberra.
"Obviously that is disappointing and we will be raising that too with Chinese government officials," Mr Pyne said.
"In terms of Mr Yang's welfare, it's not immediately apparent that has had any impact on it, but obviously that's the kind of information that we're trying to access."
Foreign Minister Marise Payne said Australia expected consular access to Mr Yang as soon as possible.
"We are also seeking, as a government, further clarification from the Chinese authorities as a priority on the nature of the detention and of any possible charges against Mr Yang," Senator Payne told reporters in Sydney.
"We will continue to make representations to China to ensure this matter is dealt with transparently and fairly."
Senator Payne said that at this stage there was no evidence to suggest Mr Yang's detention was connected to international tensions around Chinese telco Huawei.
"We're seeking clarification on those matters. I'd be concerned if there was an indication of that," she said.
The alarm was raised about Dr Yang's whereabouts after he failed to complete the second leg of a journey from New York to Shanghai.
He left New York on January 18 for Guangzhou, where he was prevented from boarding his connecting flight to Shanghai with his wife and daughter.
Similar concerns were raised for Dr Yang's safety in 2011 when he disappeared after calling a friend from a Chinese airport claiming he was being followed by three men.
He later claimed the matter had been a "misunderstanding".
Labor leader Bill Shorten said the "surprising and concerning" situation could not be sugar-coated.
"I'm very supportive of all efforts to reach out to him, to get to the bottom of what happened, what is happening," he said.
"But it is very concerning. I can't pretend otherwise."
Mr Shorten said it was disappointing China took five days to involve Australia in the incident.
"This is not the way which relations between our two countries should be conducted at all."
Australian Associated Press