A Chinese-Australian writer who was formally arrested in China on suspicion of espionage in August has been detained in "unacceptable" conditions and has been subject to daily interrogations, Australia's foreign minister said Monday.

Marise Payne said in a statement that she is "very concerned" by the reports she received after a recent consular visit to Yang Hengjun, who was detained by the Chinese government early this year.

"His circumstances of detention include increased isolation from the outside world, with restrictions on his communications with family and friends, and the resumption of daily interrogation, including while shackled," Payne said. "This is unacceptable."

Yang, a former Chinese diplomat who lived in the United States prior to his arrest, has been openly critical of the Chinese Communist Party in the past.

Payne said that despite the Australian government making repeated requests to Chinese authorities for Yang to be treated humanely and in line with international norms, there have been no substantive changes to his conditions.

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