Several employees of a famous bookstore in Hong Kong have disappeared over the past months. The "Causeway Bay" bookshop is known for selling books critical of members of China's ruling Communist Party. Reportedly, the store was planning to release a book about the love life of Chinese President Xi Jinping.

For the first time, the Chinese police admitted on Thursday, February 4, that three of the employees have been in their custody on mainland China. Two other employees of the bookshop are still missing.

In a letter to the Hong Kong Police Force, the police authorities of China's southern Guangdong Province wrote that the three employees were being held for undertaking "illegal activities on the mainland."

The mysterious disappearance of the booksellers had led to speculations that they might have been taken by Chinese agents.

Britain returned Hong Kong to China in 1997. Since then, Hong Kong has been governed under the "one country, two systems" principle, which also guarantees freedom of speech in the city. Under Hong Kong's Basic Law, Chinese security forces have no right to operate in the semi-autonomous region.

Details about the disappearances are still unclear. But the incident reinforces concerns that Beijing is increasingly trying to restrict the freedom of expression in Hong Kong.

The detention of the booksellers is likely to intimidate others. Many journalists and publishers will now think twice about what to publish and what not. With the possible threats that they could face from Chinese authorities, their concerns seem justified.

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