BEIJING — The lawyer for a Sydney-based professor who was prevented from leaving China said Sunday that his client has been allowed to return to Australia, apparently bringing closure to an incident that raised concerns about the safety of conducting academic research in China.

The barring of associate professor Feng Chongyi from leaving the country had prompted diplomatic appeals from Australia and an open letter to China’s leaders from dozens of academics.

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, where Feng had traveled during his most recent visit.

‘‘By request of the state security department, I am unable to discuss the contents of the discussions,’’ Chen said by telephone. Chen said that while Feng was not able to leave China, he had never been in formal detention.

Feng told reporters in Australia on Sunday that he wasn’t sure why he was allowed to leave China, but suspected international pressure may have played a role. He said he was unable to discuss the details of his experience.

Chinese Foreign Ministry spokesman Lu Kang said Thursday that Chinese law enforcement authorities acted ‘‘while performing duties of safeguarding national security.’’ Feng had been wrapping up a three-week trip researching human rights lawyers.