A Sydney professor and critic of growing Chinese government influence in Australia has been prevented from boarding a flight to return home to Sydney, and the ABC understands he has been told he is not allowed to leave China.

Chongyi Feng, an Associate Professor in Chinese Studies at the University of Technology Sydney (UTS), had been visiting China but friends say he was stopped from taking a flight to Australia while at Guangzhou airport in southern China on Saturday night.

It was the second time in as many days that the prominent Sydney-based academic and China expert had been blocked from boarding a flight.

During a brief phone call that cut out, he also declined to give a reason, or discuss his situation in detail.

Friends based in Australia say it isa positive sign that he is not being held completely incommunicado.

A staff member at a Guangzhou hotel where some friends claimed Dr Feng was being held said his name did not match anyone on its guest list.

"The Australian Government is aware that a UTS professor, who is an Australian permanent resident, has been prevented from leaving China," a spokesperson for the Department of Foreign Affairs said.

"The Australian Government is able to provide consular assistance only to Australian citizens who have entered China on their Australian passport."

Dr Feng is prominent in Australia's Chinese community, having previously been the head of Chinese Studies at UTS for 11 years, and was at one point a newspaper publisher.

More recently he had been vocal about the growing control and influence of Beijing on