One of five missing persons associated with a Hong Kong bookstore is a British citizen, the UK’s Foreign and Commonwealth Office confirmed on Tuesday.

Five staff from Causeway Bay Books have been reported missing since October last year: one was last seen in Thailand whilst three others were last seen across the border from Hong Kong in Shenzhen. The bookstore is popular among mainland tourists keen to buy titles banned in the mainland.

The latest to go missing, Lee Bo, was last seen on December 30 in Chai Wan, Hong Kong. In a letter allegedly written by him to his wife, Lee wrote: “I have returned to the mainland by my own method to assist the investigation by related authorities.”

Speculation about Lee’s possible British citizenship began when the daughter of Gui Minhai—another missing person associated with the bookstore—sought assistance from police in the UK, where she is studying.

Lee Bo. File Photo: Apple Daily.

HKFP received a statement from the British Foreign and Commonwealth Office through the British Consulate-General in Hong Kong.

A British Foreign and Commonwealth Office spokesperson said: “We are deeply concerned by reports about the disappearance and detention of individuals associated with the Causeway Bay Books bookstore in Hong Kong.”

“We can confirm that one of the individuals is a British Citizen and we have urgently requested the Hong Kong and mainland authorities’ assistance in ascertaining this individual’s welfare and whereabouts. We stand ready to provide consular assistance.”

“We encourage the Hong Kong SAR Government to honour its commitment to protecting the freedom of the press, and we hope the Chinese authorities will continue to make every effort to ensure that the environment in which the media and publishers operate in the Hong Kong SAR supports full and frank reporting.”

The statement did not identify which of the missing persons is a UK citizen. However, the BBC’s Chinese service has reported that the individual referred to is in fact Lee Bo.

On Tuesday, Chief Executive Leung Chun-ying said that the missing person cases were still being investigated.

“I hope anyone, especially Lee Bo himself, can provide relevant information,” he said.