TAIPEI, Taiwan — The disappearance of a Taiwanese activist for human rights and democratic causes has raised fears here that he may have been detained by the Chinese authorities.
The man, Lee Ming-cheh, has not been heard from since last Sunday morning, when he boarded a flight from Taipei to Macau, according to friends and relatives. A friend went to the airport in Macau to meet him, but he never emerged from the arrivals gate, said Cheng Shiow-jiuan, the director of Taipei Wenshan Community College, where Mr. Lee is a manager.
Mr. Lee had crossed from Macau into mainland China on Sunday, but his whereabouts have been a mystery since then, Taiwan’s Mainland Affairs Council, a cabinet-level agency that deals with China-related issues, said this week.
China has released no statements about Mr. Lee.
“The fact that Lee Ming-cheh has gone missing once again raises serious questions about the safety of people working with civil society in China,” Nicholas Bequelin, Amnesty International’s East Asia director, said in a statement on Friday.
Macau, like nearby Hong Kong, is a semiautonomous Chinese territory responsible for administering its own borders and immigration. But the unprecedented spiriting away of five Hong Kong publishers to mainland China, along with the apparent seizure of a Chinese billionaire from his serviced apartment in Hong Kong more recently, has raised concerns that China’s government no longer respects those borders.
Chiu Chiu-cheng, a spokesman for the Mainland Affairs Council, noted at a news conference on Thursday that a strict law regulating the activities of foreign nongovernmental organizations in China went into effect this year. That may have increased risks for Taiwanese people engaging with mainland Chinese involved in civil society, Mr. Chiu said.
Ms. Cheng, the director of the community college, said on Saturday that Mr. Lee had not been directly involved with civil society work in mainland China.
But she said his wife, Lee Ching-yu, had told her that he had weekly chats on Chinese social media about “some of Taiwan’s experiences with democracy and transitional justice” with mainland friends who wanted China to move in a direction similar to Taiwan’s.
Such discussions are dangerous in China, where state surveillance of the internet is pervasive and comments critical of the ruling Communist Party can draw swift punishment.
Mr. Lee met with some of those friends during visits to the mainland about once a year, Ms. Cheng said.
“It’s not any kind of formal activity; it’s just catching up with friends,” she said. She added that he also delivered donated Taiwanese books to the family of imprisoned rights lawyers in China and had planned to seek medical advice for a relative during this week’s trip.
Ms. Lee was unavailable for comment on Saturday.
Beijing views self-governed, democratic Taiwan as a renegade province that must eventually be reunited with China — by force if necessary. Some Taiwanese news outlets have speculated that Mr. Lee’s disappearance could be retribution for the arrest this month of a Chinese national accused of espionage.
Mr. Lee has long been active in pro-democratic and human rights causes. Ms. Cheng described him as a dedicated manager who had made a deep impression on others since joining the community college’s planning department in February 2016.
Eeling Chiu, secretary of the Taiwan Association for Human Rights, said on Friday that Mr. Lee’s disappearance was the first case of a Taiwanese worker for a nongovernmental organization going missing after entering China.
Mr. Lee does not work for the association, but he has done volunteer work for an umbrella organization to which it belongs, called Covenants Watch.
Ms. Chiu called on the Chinese government to release images of Mr. Lee as he passed through customs to prove that he had not been detained at the border.