An outspoken Australian writer and political commentator who formerly held Chinese nationality is under "coercive measures" in Beijing on suspicion of "endangering national security," China's foreign ministry confirmed on Thursday. Yang Hengjun, whose name at birth was Yang Jun, was detained on arrival at Guangzhou Airport on Jan. 19, then taken to Beijing by officers of the state security police, according to friends and eyewitnesses. Dr Yang, whose legal name is Yang Jun, was a former employee at China's ministries of foreign affairs and state security before migrating to Australia where he reportedly obtained his citizenship in 2002. The 53-year-old had been living with his family in New York, where he has been a visiting scholar at Columbia University since 2017, before his arrest at Guangzhou airport in southern China earlier this month. In addition to Dr Yang's recent academic role, he has worn many hats over the years: an author of spy novels, a prominent blogger, an outspoken political commentator as well as a democracy advocate. "According to our understanding, the Australian national Yang Jun is suspected of engaging in criminal activities endangering China's national security, was recently placed under coercive measures and is being investigated by the Beijing municipal state security bureau," foreign ministry spokeswoman Hua Chunying told a regular news briefing in Beijing. "Coercive measures" generally refers to detention in a location other than a police-run detention center, possibly a guesthouse or other property where the detainee is held incommunicado. "At present, the case is being handled according to law, and Yang Hengjun's legitimate rights and interests have been fully guaranteed," she said. Chinese law allows police to detain those suspected of vaguely worded "national security" crimes and hold them under residential surveillance at a secret location for up to six months, with no access to lawyers or family visits. Yang's lawyer Mo Shaoping confirmed that his client is being held under "residential surveillance at a designated location." "We don't know the exact charges yet, but Yang Hengjun is suspected of espionage," Mo said. "But even we, his lawyers, don't have the details." "We haven't seen any of the evidence in the state security bureau's case files," he said. "Our next step will be to get in contact with the Beijing municipal state security bureau and go through the necessary procedures as his lawyers, and to request a meeting with him." Yang's detention comes amid growing international tension over the detention in Canada of Meng Wanzhou, chief financial officer of China's flagship telecommunications firm Huawei. Thirteen Canadians were detained in China after the ruling Chinese Communist Party vowed to retaliate for the arrest of Meng, who is wanted for questioning by investigators in the U.S. over alleged bank fraud linked to the breach of sanctions against Iran. 'The actions of terrorists and bandits' While at least eight have since been released, a court in the northeastern Chinese province of Liaoning handed down the death penalty to Canadian Robert Schellenberg after a review of his 15-year drug-smuggling sentence in the wake of Meng's arrest. Both the U.S. and Canada have now upgraded cautionary advice to any of their citizens traveling to China, amid growing calls for the release of former Canadian diplomat Michael Kovrig and consultant Michael Spavor, who are also being detained on suspicion of "endangering state security." Australian Defence Minister Christopher Pyne, who arrived in Beijing on a long-planned trip on Thursday, said Australia wasn't notified of Yang's detention until four days later, past the three-day legal requirement for such notifications. "He's being held in residential surveillance," Pyne told reporters, adding that he would bring up the issue in talks with Chinese officials. Yang's friend and Sydney-based university lecturer Feng Chongyi said Yang's wife and stepdaughter are still with relatives in Shanghai, where they have been warned not to speak to the press about the situation. Feng said he doesn't believe the police have any real evidence to substantiate the charges of endangering state security, and that his detention is likely the result of Australia's recent expression of "concern" for Kovrig and Spavor. Feng said it was important not to waver when confronting Beijing with the recent string of detentions, which he linked to Meng's arrest. "You can't show any weakness, nor can you make any concessions or back down," Feng said. "All democratic countries should join hands and protect their red lines[and let China know that] they can't ignore international law and the most basic humanitarian requirements and just go around randomly detaining people." "These are the actions of terrorists and bandits," he said.