HONG KONG (Bloomberg) - Hong Kong's police department is investigating the reported disappearance of people related to a bookstore in the city, Chief Secretary Carrie Lam said.

Mr Lee Bo, a major shareholder of Causeway Bay Books, which specialises in reading material critical of the Chinese Communist Party, went missing and his wife reported his disappearance on Friday (Jan 1) afternoon, the South China Morning Post said on Saturday. The disappearance of Mr Lee, 65, comes weeks after four people related to the bookstore and its owner vanished, the newspaper said.

The Hong Kong government cares about the well-being of its people whether they are in the city or travelling abroad, Ms Lam told reporters on Saturday (Jan 2) after attending an event, according to a statement from her office. She declined to comment further, given the police investigation.

Mr Gui Minhai, the owner of Mighty Current, the publishing house which owns the bookstore, turned up in Thailand after leaving town, the South China Morning Post reported, without saying how it obtained the information.

The bookstore's manager Lam Wing-kei; Mr Lui Bo, general manager of the publishing house; and Mr Cheung Jiping, the publishing house's business manager, were reported missing Nov 5, according to the report.

The bookstore, established in 1994, was said to be popular among tourists from China's mainland as they could buy political material banned across the border, according to the newspaper.