An Australian writer who many consider to be the most influential political commentator on the Chinese language internet has disappeared, apparently at the hands of Chinese police.

Yang Hengjun, who retired from the Chinese Foreign Ministry to become a Sydney-based spy novelist, intellectual and blogger, has not been seen since phoning a colleague from Guangzhou airport on Sunday with news that he was being followed by three men.

Yang Hengjun ... respected commentator. Credit:Tanya Lake

If Dr Yang does not promptly reappear, then his name will be added to the list of challenges facing Julia Gillard when she arrives in Beijing next month for her first visit as prime minister.

Mr Yang is understood to carry an Australian passport. Others on her list of Chinese-Australians who have fallen foul of China's capricious justice system include Matthew Ng, a successful entrepreneurs in China, and the iron ore salesman Stern Hu.

Mr Ng, who also disappeared in Guangzhou before being charged with embezzlement, remains in a legal limbo until his file is transferred to prosecutors. Mr Hu, the Rio Tinto executive, was sentenced a year ago to 10 years in jail for receiving bribes and commercial secrets.

''Yang Hengjun is the most influential political blogger in China, with millions of readers'' said Feng Chongyi, who supervised Dr Yang's PhD thesis at the University of Technology, Sydney.

Friends and colleagues said they believed Dr Yang was the latest and most prominent victim of Beijing's pre-emptive and iron-fisted response to the ''jasmine revolutions'' that have swept the Middle East.