Yang Hengjun, an Australian citizen, has been detained for over two years after his arrest at an airport in 2019, reports BBC.

Beijing has revealed next to no details about the charges he faces, leading Australia to contend he is suffering an "arbitrary detention", the British media reported.

The development took place amid deteriorating relations between Australia and China.

On Thursday, Australian diplomats were turned away from entering his courtroom. Applications had also been rejected for Yang's relatives, reports BBC.

"This is deeply regrettable, concerning and unsatisfactory," Australia's ambassador to China Graham Fletcher told reporters outside the court.