China’s foreign ministry says that Chinese-Australian blogger, novelist and former Chinese diplomat Yang Hengjun was detained on charges of endangering national security.

Speaking at a daily press briefing in Beijing Thursday, foreign ministry spokeswoman Hua Chunying offered few details about the case but confirmed Yang’s arrest on suspicion of “criminal activities,” the Associated Press reports. China’s vague national security laws are commonly used to target critics of the ruling Communist Party.

Yang, 53, was due to arrive in the Chinese city of Guangzhou early on Dec. 19 and then travel on to Shanghai with his family. But he never cleared security for the second leg of the journey, said Feng Chongyi, an associate professor in China studies at the University of Technology Sydney. Yang reportedly told Feng that his trip to China would not attract any attention from authorities, the Sydney Morning Herald reports.

A Wednesday statement from Australia’s Department of Foreign Affairs and Trade said the government was “seeking to clarify the nature of this detention and to obtain consular access to him.” Australian officials were due to meet with Chinese authorities in Beijing Thursday to learn more about the situation.

Yang, an Australian citizen since the early 2000s who has been living in the U.S. for several years, is known for his spy novels and calls for democracy and reform in China. He has a large online following, and his views have earned him the nickname “Democracy Peddler” in some circles, according to the BBC.

Yang is the latest in a series of foreign nationals to be detained by China in recent months. Following the December arrest in Canada of Meng Wanzhou, a high-ranking executive of Chinese technology firm Huawei, Beijing arrested two Canadians — Michael Spavor and Michael Kovrig. The government of Canada later said more than a dozen of its citizens had been detained, most of them released.

Neither is this Yang’s first run-in with Chinese authorities. He briefly disappeared in 2011 after calling a friend from a Chinese airport to say he was being followed. He later said the matter had been a “misunderstanding.” He was also reportedly questioned by authorities during a 2017 visit to China.

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Write to Kamakshi Ayyar at kamakshi.ayyar@time.com.