Yang wore goggles, a face mask and full pandemic suit that obscured his expression as he addressed the court hearing on Thursday, his friends have told Reuters.

He wrote pages of defence material that was presented to the court, and also briefly spoke, Reuters was told.

Australian consular officials visited Yang in detention on Friday, after being denied access to the court on Thursday. Australia has not been informed of any details of the charges or investigation, Payne said in a statement.

"We consider this to be an instance of arbitrary detention of an Australian citizen," she said.

Australia's ambassador to China was denied entry to the Beijing No.2 Intermediate People's Court on Thursday, prompting a rebuke from China, which said the case involved state secrets so could not be heard in the open.

Yang's wife was also refused permission to attend, and has been unable to see him since he was detained. read more

An Australian citizen born in China, Yang wrote about Chinese and U.S. politics online as a high-profile blogger and also penned a series of spy novels.

Immediately before his detention he had been living in New York, where he was a visiting fellow at Columbia University.

He was detained two years ago as he entered China at Guangzhou airport, and has denied the allegations against him.

Yang's lawyers, who include prominent Chinese human rights lawyer Mo Shaoping, have been forbidden from speaking to his family or the Australian government about details of the charges against him, or the nature of the evidence in the case.

The Chinese foreign ministry didn't immediately respond to a request for comment.

Chinese Foreign Ministry spokesman Zhao Lijian on Thursday accused Australia of meddling in China's judicial sovereignty by seeking access to the court hearing.

"Chinese judicial authorities had handled the case in strict accordance with the law, fully protected Yang Hengjun's litigation rights," he told a press briefing on Thursday.