BEIJING — A Chinese-born professor at an Australian university who has often criticized Beijing’s crackdown on political dissent has been barred from leaving China and is being questioned by state security officers as a suspected threat to national security, his lawyer said on Sunday.
The confinement of Feng Chongyi, an associate professor at the University of Technology Sydney, or U.T.S., unfolded over the weekend while China’s premier, Li Keqiang, visited Australia to promote deeper trade and diplomatic ties. Professor Feng’s case could cloud those ties.
The lawyer, Chen Jinxue, said Professor Feng had not been arrested or formally charged.
The professor has been staying in a hotel in Guangzhou, a city in southern China, and has been repeatedly questioned by national security officers after being stopped by entry-exit checkpoint officials on Friday and Saturday from taking flights back to Australia, Mr. Chen said from Guangzhou, where he was accompanying Professor Feng.
“He’s been told he’s suspected of involvement in a threat to national security,” Mr. Chen said by telephone, adding that Professor Feng declined to comment.
“His movements inside China aren’t officially restricted, but national security authorities have questioned him a number of times about who he’s met and that kind of thing,” the lawyer added. “They’ve told him that he’ll have to stay around for at least a couple more days to answer their questions.”
Professor Feng has been researching Chinese human rights lawyers, who have been subjected to a withering crackdown and detentions since 2015, and that work may have caught the attention of security investigators, Mr. Chen said.
Mr. Li, the Chinese premier, ended a five-day visit to Australia on Sunday, and it was unclear whether the professor came up during his talks with Australian politicians. But that nation’s Department of Foreign Affairs and Trade said it could not demand to see Professor Feng because he is not an Australian citizen.
“The Australian Government is aware that a U.T.S. professor, who is an Australian permanent resident, has been prevented from leaving China,” the department said in an email. Under an agreement with China, the department said, “the Australian government is able to provide consular assistance only to Australian citizens who have entered China on their Australian passport.”
Professor Feng, 56, was born in southern China. His lawyer confirmed he has permanent residence in Australia and was not a citizen. Even so, the case has ignited demands that the Australian government do more to secure his quick release.
“We are urging the Australian government to intervene,” John Hu, a spokesman in Sydney for the Embracing Australian Values Alliance, which has sought to promote free speech and counter the Chinese government’s influence over the ethnic Chinese community in Australia.
“Right now the excuse for their inaction is that Chongyi Feng is only a permanent resident but not a citizen,” said Mr. Hu, who is a friend of Mr. Feng’s. “Feng has not breached the Chinese law — his doings were not even in China’s jurisdiction, and the Chinese government has no right to persecute him.”
The university has been in contact with Professor Feng and was helping his family, Greg Walsh, a university spokesman, said by email.
The professor is probably better known in Chinese intellectual circles than in Australia. A historian, he has long been involved in debates about China’s future, advocating a path of political liberalization.
He has also criticized the Chinese government’s increasing efforts to exert influence over ethnic Chinese in Australia. Last year, he spoke out against plans for concerts honoring Mao Zedong in Sydney Town Hall and Melbourne Town Hall.
“Australia is proud of its commitment to free speech, tolerance and cultural diversity,” he wrote. “However, should intolerance be tolerated? Should lies about Mao and promotion of Maoism, which denies freedom of speech, be allowed as a legitimate part of free speech?”
With its growing ethnic Chinese population and growing economic ties to China, Australia has experienced a succession of cases of residents or citizens being detained in China, creating tensions over their legal rights and access to Australian diplomats. In 2011, Yang Hengjun, a writer and former Chinese official who had migrated to Australia, was detained for days in Guangzhou by security officials.
Until the 1960s, Australia excluded Chinese migrants through the “White Australia” policy. In recent decades, the number of migrants from China has grown drastically, and by 2015, nearly 500,000 of Australia’s 24 million residents had been born in China.
The disappearance of those seen as acting against China’s interests has stirred concerns in other territories. A Taiwanese activist for human rights and democratic rights, Lee Ming-cheh, has been missing since last Sunday morning, when he boarded a flight from Taipei to Macau but never emerged from the arrivals gate. His friends and family fear he may have been detained by the Chinese authorities.
As the Chinese president, Xi Jinping, has clamped down on dissent, Professor Feng and other advocates of political relaxation have no longer been able to write for the domestic Chinese news media. But on overseas Chinese websites and in interviews with foreign journalists, he has sharply criticized Beijing’s clampdown.
“Since Xi Jinping came to office, he has not only failed to lead China forward in reform and opening up and constitutional government, he has made an historical U-turn,” he wrote last year.