Pro-democracy blogger Yang is an Australian citizen born in China who was working in New York before his arrest at Guangzhou airport in 2019. His arrest coincided with a deterioration in relations between Australia and China and a verdict in his case has been repeatedly delayed.

A Beijing court heard Yang's trial in secret in May 2021 and the case against him has never been publicly disclosed. He has denied working as a spy for Australia or the United States. After 10 delays, a verdict in his case is due in October.

The Australian Embassy in Beijing visited Yang on Friday and was told he had a 10 cm (4 inch) cyst on his kidney that may require surgery, heightening concerns for his health, said Feng Chongyi, a friend and former academic supervisor at the University of Technology, Sydney, who has been briefed on the matter.

"I think this is a strong case for the Australian government to demand for Yang's release to Australia on medical parole," Feng said.

Yang's case, and that of detained Australian journalist Cheng Lei, tried in secret on national security charges in March 2022, are being closely watched in Australia ahead of an anticipated visit by Prime Minister Anthony Albanese to Beijing this year.

Albanese told reporters on Monday he would raise the concerns about Yang's health when he meets Chinese President Xi Jinping at the G20 meeting next month.

"We always raise issues of Australian citizens where either myself or my ministers meet with our international counterparts," he said, when asked about Yang's case.

A spokesperson for Australia's Foreign Minister Penny Wong said the Australian government shared the concerns of Yang's friends and family about delays in his case, and had called for basic standards of justice and medical treatment.

"The Australian government has consistently advocated for Dr Yang's interests and wellbeing, and for him to be reunited with his family," she said.

His case was raised with China in bilateral consular meetings, which resumed last week.

China's foreign ministry has previously said Australia should not interfere in the case.

Yang said in a message to his friends that he was concerned about an article online accusing him of being recruited by a CIA agent posing as an exchange student in Shanghai in the 1980s, which he strongly denied.

Feng said Yang's supporters are worried his case will be used by the Chinese government to highlight its counter-espionage campaign.

Relations between the United States and China have soured in recent years over a range of issues, including national security with both sides accusing the other of espionage.

China expanded its anti-spying law in July, alarming the United States.

The Chinese embassy in Australia and the Chinese foreign ministry did not immediately respond to requests for comment.

(Reporting by Kirsty Needham: Additional reporting by Laurie Chen in Beijing, Alasdair Pal in Sydney: Editing by Neil Fullick)

By Kirsty Needham