Chinese police officials broke their silence on the disappearance of Hong Kong book seller Lee Bo, reportedly acknowledging Lee’s presence in China in a letter sent to Hong Kong media. Friday’s statement emphasized that Lee was in the mainland of his own free will, but offered no fresh information about his situation.

The 65-year old book publisher of Hong Kong’s Causeway Books – known printing and selling books critical of Chinese leaders – went missing in late December, following the disappearance in recent months of four other people connected to the bookstore. Lee, who holds a dual British and Chinese citizenship, was met by his wife at a guest house in China last week.

Lee looked healthy and in good spirits, his wife had reportedly said, adding that he told her he was assisting the Chinese Police in an investigation as a witness.

The disappearances have prompted widespread protests in Hong Kong over a perceived Chinese clamp down on Hong Kong media and concerns over its tactics to circumvent the “one country two systems” formula under which Hong Kong, while governed by China, enjoys a certain autonomous relationship with the mainland.

“If there is news, we will notify (Hong Kong) in a timely fashion,” Friday’s letter reportedly said.

Sent by the Police officials in the southern Chinese province of Guangdong , the brief letter did not address a request by Hong Kong officials to arrange a meeting with Lee. The letter repeated some of the information already made public by Hong Kong Police – that Lee was "understood" to be on the mainland, and Lee had come to the mainland on his own accord – local media reports said.

Lee’s disappearance followed two months after four of his business associates, Gui Minhai, Lui Por, Cheung Ji-ping and Lam Wing-kei, disappeared separately in October.

Swedish citizen Gui Minhai, who was in Thailand at the time of his disappearance, appeared on Chinese state television earlier in January, saying he had surrendered to authorities over a fatal drink-driving offence more than a decade ago.

The British government is still waiting for responses to its diplomatic requests for information and access to Lee, Reuters reported.