A law enforcement body in China has warned Hong Kong bookseller Lam Wing-kee that he could face harsher legal action for violating his bail conditions after he was allowed to return to Hong Kong in June, a Hong Kong newspaper reported.
A statement issued by the Ningbo Public Security Bureau said Lam had broken his bail terms by failing to return to the mainland for further investigation after an initial eight months in detention, Hong Kong's Ming Pao newspaper reported.
Lam was one of five booksellers whose disappearances over the past year have been linked to the Causeway Bay Books store that had specialized in publishing and selling gossipy books about China's leaders, including President Xi Jinping.
The Ningbo Public Security Bureau said unspecified criminal enforcement measures would be triggered by his failure to return.
The bureau did not respond immediately for comment, and Lam could not be reached.
The South China Morning Post reported that Chinese authorities had released a video of Lam during his time in detention. In a video link on the newspaper's website, Lam could be seen eating, being given a haircut and making comments.
On his return to Hong Kong last month, Lam said Lee Bo, who went missing from Hong Kong in late December, had been abducted, and said "cross-border enforcement actions" by mainland Chinese authorities in Hong Kong were "not acceptable".
Lam said he was arrested last October in the southern Chinese city of Shenzhen and blindfolded and taken to the eastern city of Ningbo, where he was kept in a small room by himself and repeatedly interrogated about the selling of books banned on the mainland.
The disappearances have prompted fears that mainland Chinese authorities may be using tactics that erode the "one country, two systems" formula under which Hong Kong has been governed since its return to China from British rule in 1997.
Public security minister Guo Shengkun met a Hong Kong delegation in Beijing on Tuesday to discuss the detainee notification system between the two police forces, which needs to be "modified and improved", the ministry said.
The delegation was also briefed on Lam's case, Xinhua news agency added, without elaborating.
Hong Kong enjoys far wider personal freedoms and protections than exist on the mainland. No formal extradition treaty exists between the two jurisdictions.
Lam pulled out of a protest march in Hong Kong on July 1, citing concerns for his personal safety after he noticed several people following him in recent days.
Hong Kong police said after meeting Lam on Monday there was no evidence his personal safety was at risk. They advised him to call for police assistance if needed, a police statement said.