CANBERRA, Australia (AP) — A Chinese Australian writer detained in Beijing since January has been charged with endangering state security and moved from house arrest to a detention center, his lawyer and a friend said Thursday.

China said Yang Hengjun's case was under investigation by the Chinese national security department but hasn't elaborated on the accusations.

Australian lawyer Rob Stary said he had been told by Yang's family and friends of the charge and was seeking confirmation from Australia's Department of Foreign Affairs and Trade. Stary did not have details of the charge.

Yang's friend, University of Technology Sydney academic Feng Chongyi, said Yang's wife, Xiaoliang Yuan, on Thursday was shown written notice of the charge, endangering state security, a vague offense that includes espionage and carries potential penalties of between five years in prison and execution. The charge has frequently been made against critics of China's ruling Communist Party.

The 53-year-old visiting scholar at Columbia University in New York had been moved to Beijing national security department detention center where his living conditions would be much better than they have been for the past six months, said Feng, who was detained for two weeks in 2017 while visiting China to research human rights lawyers.

Yang had previously been held under so-called residential surveillance at a designated location. This can involve being guarded 24-hours a day with lights on continuously and tortures including sleep deprivation, being tied to a chair or forced to stand for hours, Feng said.

In formal detention, Yang would be allowed to mix with other inmates, watch television and go outside into the sunshine twice a day, Feng said.

Feng said while some would argue that Yang had not been formally charged until a lawsuit is issued, perhaps in several months, he effectively has been charged.

"I only hope the Australian government can do more to press for his release," Feng said.

The Department of Foreign Affairs and Trade said the Australian Embassy was seeking confirmation that Yang had been transferred to a Beijing detention center. The embassy had been notified of the transfer by Yang's family.

"Australia continues to have consular access and have again asked that he be granted immediate access to his lawyers," the department said in a statement.

The Chinese Foreign Ministry confirmed the national security department was handling Yang's case.

Ministry spokesman Lu Kang said on Thursday: "At present, the case is under investigation."

"The Chinese national security department handles the case in strict accordance with law and fully protects Yang Jun's lawful rights," Lu said, referring to Yang by a name he is also known by.

He has been detained since Jan. 19, when he arrived from New York at China's Guangzhou Airport with his wife and his 14-year-old stepdaughter.

Foreign Minister Marise Payne did not respond to a request for comment on Thursday.

Feng suspects Yang was detained in retaliation for the December arrest of Meng Wanzhou, the chief financial officer of Chinese tech giant Huawei, in Canada on a U.S. warrant. The arrests of two Canadians in China were widely suspected as such, and Payne has previously said Australia's government would be concerned if Yang's detention was related to the other cases.

Feng said Australia should work with other countries including the United States and Britain to stop China for taking such retaliation against other nation's citizens.

"They have taken some many hostages around the world, there needs to be collective action to block the Chinese government from doing these terrible things," Feng said.

Payne said last week that her government had raised Yang's case "regularly with China at senior levels."

"We have requested his case be treated fairly, transparently, and expeditiously," Payne said in a statement.

"Australia has asked for clarification regarding the reasons for his detention and we have said that if he is being detained purely for his political views, then he should be released," she added.

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Associated Press researcher Liu Zheng in Beijing contributed to this report.