Morrison Lee (right) (Source: CNA)

Morrison Lee (right) (Source: CNA)

[Updated with a statement from the Presidential Office at 14:00 Sept. 11]

TAIPEI (Taiwan News) — The Chinese authorities have confirmed that Morrison Lee (李孟居), a Taiwanese man who went missing during his transit from Hong Kong to China in August, is in custody.

Lee has been detained for “committing criminal activities that jeopardize national security,” said Ma Xiaoguang (馬曉光), spokesperson for the Taiwan Affairs Office, a Chinese government agency implementing Beijing’s policy toward Taiwan, at a press briefing on Wednesday (Sept. 11). He is “being investigated according to the law,” Ma said, without providing other information.

An advisor to the Fangliao Township Office in Pingtung County, Lee took a trip to Hong Kong on August 18 and had plans to travel to the bordering Chinese city of Shenzhen two days later. He has not been heard from since entering China, his family said.

“We are highly concerned” about Lee’s detention by China, said the Presidential Office via a statement on Wednesday afternoon. The government is in negotiations with the Chinese authorities to ensure Lee’s safety and rights and will provide necessary assistance.

During a press conference at the end of August, Mainland Affairs Council (MAC) Spokesperson Chiu Chui-cheng (邱垂正) said the government has made inquiries to both Hong Kong and Chinese authorities about Lee’s whereabouts. Chiu added that Beijing had not responded at that time.

Bloomberg News previously reported that Lee had attended one of the anti-extradition bill protests in Hong Kong. He originally planned to visit Indonesia after wrapping up his trip to China.

Lee is the second Taiwanese to be detained by the Chinese authorities over alleged national security concerns after President Tsai Ing-wen (蔡英文) of the independence-leaning Democratic Progressive Party (DPP) took office in 2016. Pro-democracy activist Lee Ming-che (李明哲) was sentenced to five years in prison in 2017 for “attempting to subvert state power.”

The cross-strait relations have become increasingly strained in recent years. The Taiwanese authorities have warned of Beijing’s interference in the presidential election next January, while China has accused the DPP-ruled government of dipping its “black hands” into Hong Kong’s months-long civil unrest.