The trial of Australian journalist Cheng Lei on charges of espionage has begun in Beijing behind closed doors. Diplomats have been denied permission to attend proceedings, taking place under heavy guard.

The Australian envoy to China, Graham Fletcher, was barred from entering the court.

"We have been denied entry into the trial," Fletcher told the media outside the Beijing court on Thursday.

"This is deeply concerning, unsatisfactory and very regrettable. We can have no confidence in the validity of a process which is conducted in secret."

Australian journalist detained for almost 19 months

Cheng — a former anchor for the state-owned China Global Television Network — has been held for nearly 19 months on accusations of supplying state secrets abroad.

China has not provided any further details about the offenses Cheng is alleged to have committed.

Cheng's family said they had been informed of the trial and thanked Australia's diplomats for their support.

"Her two children and elderly parents miss her immensely and sincerely hope to reunite with her as soon as possible," said a family statement that was forwarded by the foreign ministry in Canberra.

Cheng could face a life sentence in prison if she is found guilty of violating China's national security laws.

Worries over Cheng's detention conditions

There have been concerns in Australia over Cheng's welfare and her detention conditions.

Australian Foreign Minister Marise Payne had last week called on China to meet  "basic standards of justice, procedural fairness and humane treatment [...] in accordance with international norms."

The trial comes amid strained relations between Australia and China, after Canberra called for an an international probe into the source of the COVID-19 pandemic in 2020. Beijing retaliated with trade reprisals.

dvv/kb (AFP, AP, Reuters)