Another delay in the verdict for Australian writer Yang Henjun has been met with deep disappointment by supporters and the government.

Dr Yang has been detained in China for four years on espionage charges, with a verdict delayed for a seventh time – until April.

Foreign Minister Penny Wong said Australia is “deeply troubled by the ongoing delays in his case”.

“Our thoughts are with Dr Yang and his family,” she said.

“The Australian government has called for basic standards of justice, procedural fairness and humane treatment to be afforded to Dr Yang, in accordance with international norms and China’s legal obligations.”

Senator Wong said the government will continue to advocate for Dr Yang’s wellbeing at the highest level and provide consular assistance to him and his family.

The opposition has added its voice to concerns, with foreign affairs spokesman Simon Birmingham saying the case’s uncertainty and delays are “unacceptable and unjust”.

“During this difficult time our thoughts remain with Dr Yang and his family,” he said.

“While reports have noted that Dr Yang was allowed a consular visit, the opposition remains deeply concerned for Dr Yang’s welfare as well as his limitations on access to legal representation.”

The case against the writer has never been publicly disclosed and his trial was held in secret in May 2021.

Dr Yang has denied working as a spy and his supporters have described it as political persecution over his human rights stance.

Chinese ambassador to Australia Xiao Qian has said his government could not intervene in cases that were before the courts.

A spokesperson for China’s foreign ministry said on Thursday that Australia should not interfere with China’s judicial system regarding the delay of a verdict for Dr Yang.

“Chinese judiciary has tried cases strictly in accordance with the law, fully protected the legitimate rights of the parties concerned, and fully respected and protected the consular rights of the Australian side, such as visitation,” Wang Wenbin said at a regular press briefing.

In early January consular officials were granted visits to Dr Yang and detained Australian journalist Cheng Lei, who was tried in secret on national security charges in March 2022, for the first time since October.

-with Reuters