Beijing, China — An Australian academic has been arrested in China for spying, Beijing said Tuesday, prompting Canberra to demand the country upholds “basic standards” of justice.

Yang Jun, who also goes by his pen name Yang Hengjun, was detained in January shortly after making a rare return to China from the United States.

Beijing said he was formally arrested last Friday and that the case was being “further processed.”

Australian Foreign Minister Marise Payne said earlier on Tuesday that she was “very concerned” that Yang — a former official turned author — had been arrested on “suspicion of espionage”.

“We expect that basic standards of justice and procedural fairness are met,” she added.

After months without access to his lawyer or family, Yang now faces trial on charges that could bring a lengthy prison sentence.

China’s near-silence about Yang’s fate has been a point of friction in relations with Australia that have markedly deteriorated in recent months.

In a sharply worded statement, Payne said she had raised the case five times with her Chinese counterpart Wang Yi, in person and via letters.

“Dr Yang has been held in Beijing in harsh conditions without charge for more than seven months,” Payne said, referencing international rules prohibiting torture.

“Since that time, China has not explained the reasons for Dr Yang’s detention, nor has it allowed him access to his lawyers or family visits.”

But foreign ministry spokesman Geng Shuang told reporters Tuesday that China had acted “in accordance with the law and fully guarantees the rights of Yang Jun” who he said was “currently in good health.”

He rejected criticism from Canberra over the conditions of Yang’s detention.

“The Chinese side has expressed strong dissatisfaction with the Australian side’s statement on the case,” Geng added.

“The Australian side should earnestly respect China’s judicial sovereignty and must not intervene in any way to China’s handling of the case.”