Yang Jun, who denies the spying claims, was arrested on a trip back to China in 2019. (Representational)
The sons of an Australian writer jailed in China are hoping for his "miracle" release, urging Prime Minister Anthony Albanese to raise their father's plight on a trip to Beijing.
Chinese-born Australian writer Yang Jun has been detained in China since 2019, accused of spying in a closed trial that is heavily criticised by human rights activists.
In recent weeks Yang's health has rapidly deteriorated as a large cyst grows on his kidney, with his family increasingly fearful he will be "left to die" in detention.
In an open letter released Wednesday ahead of Albanese's November trip to China, Yang's sons asked the prime minister to "do all in your power to save our father's life".
"The risk of being left to die from medical maltreatment is especially clear to our father because he has seen it happen to his friends," it read.
Australian journalist Cheng Lei, who was imprisoned in China on similarly opaque espionage charges, was freed last month after three years in detention.
Cheng's return followed sustained lobbying from the Australian government, raising hopes that Yang might also soon be released.
Yang's sons said they hoped Albanese "can achieve a second miracle by saving our father".
"Like Cheng Lei, our father cherishes the freedoms and protections that come with his Australian identity."
Albanese will meet Chinese President Xi Jinping during his visit from November 4 to November 7 -- the first by an Australian prime minister since 2016.
He told reporters on Wednesday that he would "always raise these issues and make representations on behalf of Australians".
"We are very sympathetic and understand the concerns that they would have for their father," he said.
Foreign Minister Penny Wong said she was "deeply concerned by the deterioration of Dr Yang's health".
"Since Dr Yang was detained, the Australian government has called for basic standards of justice, procedural fairness and humane treatment... in accordance with international norms and China's legal obligations," she said in a statement.
Attempts to raise Yang's situation have irked Chinese officials in the past, who have told Australia to stop meddling in the country's justice system.
Yang's sons described the "particularly cruel" treatment they believed their father was facing, deprived of his beloved books in a cramped room where he is forced to "eat, drink, defecate and urinate".
"At most, some rays of sunlight occasionally come through one or two panes of glass and flicker fitfully," Yang told his sons, according to the letter.
"And my cell is also like a hole -- I often call it 'the dungeon' because it always gives me the feeling of being in an underground cavern".
Yang, who denies the spying claims, was arrested on a rare trip back to China in January 2019.
The writer and academic, who also goes by the pen name Yang Hengjun, had previously told supporters he was tortured at a secret detention site and feared forced confessions may be used against him.
"They deprived him of sleep, strapped his wrists and ankles and pinned him to a chair for days at a time, until he couldn't walk," his sons wrote.
His closed-door trial was heard in Beijing in 2021, but the verdict has been repeatedly delayed.
(Except for the headline, this story has not been edited by NDTV staff and is published from a syndicated feed.)