Updated

The lawyer for a Sydney-based professor who was prevented from leaving China says his client has been allowed to return to Australia.

The barred departure of associate professor Feng Chongyi had prompted diplomatic appeals from Australia and an open letter to China's leaders from dozens of academics warning that the incident was raising concerns about the risks of conducting research in China.

Feng's lawyer Chen Jinxue said Feng flew home from the southern city of Guangzhou on Saturday night after a final round of questioning by security agents from the southwestern province of Yunnan. Chen said he wasn't able to disclose what topics were discussed.

Feng told reporters in Australia on Sunday that he wasn't sure why he had been released, but suspected international pressure may have played a role.