A missing Hong Kong employee from a publisher of books critical of China was "assisting in an investigation", his wife said Saturday, as police also probe the disappearance of his colleagues.
Lee Bo went missing Wednesday night and is the fifth employee of Hong Kong-based publisher Mighty Current to disappear.
The incident adds to growing unease that freedoms in the semi-autonomous Chinese city are being eroded, with fears the five men may have been detained by Chinese authorities.
"He said he wouldn't be back so soon and he was assisting in an investigation," Lee's wife Sophie Choi told Hong Kong's Cable Television, describing a call she had with Lee the night he failed to return home.
It was not clear what investigation Lee was referring to.
"I asked him if it was related to the case before. He said 'yes', regarding that case where a few others had gone missing," Choi said.
Police said in a statement they were investigating the disappearance of Lee and three of the other missing men.
It made no comment on the fifth man.
Deputy leader Carrie Lam tried to reassure the public.
"The Hong Kong government cares about its people's wellbeing... police are working on this case," she told reporters.
Choi previously told AFP she started looking for Lee on Wednesday night after he failed to return home for dinner and she reported him missing to police on Friday.
He later called to say "everything was alright" from a number that did not belong to him and originated from the neighbouring mainland Chinese city of Shenzhen, Choi had said.
Another source told AFP that Lee, 65, was last seen in Hong Kong on Wednesday at the publisher's warehouse, which he is in charge of.
- 'Concern and anxiety' -
Hong Kong was handed back to China by Britain in 1997 and enjoys liberties not seen on the mainland, but there are fears these are under threat.
The publishing company's general manager Lui Bo, an employee Cheung Jiping and bookstore manager Lam Wing-kei are also apparently missing after disappearing in southern China in October.
Local media said Gui Minhai, a Swedish national and co-owner of Mighty Current, failed to return from a holiday in Thailand in October.
Hong Kong police are investigating the disappearance of Lui, Cheung, Lam and Lee -- they gave no information on Gui.
Sweden's embassies in Bangkok and Beijing are reportedly investigating Gui's disappearance.
The Hong Kong Journalists Association sent a letter to the Chinese Liaison Office -- Beijing's representative office in the city -- urging authorities to reveal whether the men are in the mainland.
"The incident has caused a high degree of concern and anxiety to Hong Kong residents," the statement said.
Hong Kong publisher Yao Wentian, who was due to release a dissident's book about Chinese President Xi Jinping, was reported to have been detained for almost three months in January 2014.
The following May, Yao, then 73, was sentenced by a Chinese court to 10 years in jail for smuggling. afp