Beijing's Public Security Ministry has told a visiting Hong Kong government delegation that Causeway Bay bookseller Lam Wing-kee is a wanted man on the mainland and should return to face charges.
It also threatened to take unspecified action if he does not.
After returning to Hong Kong last month following his disappearance in October, Lam said he felt threatened about his personal safety, adding that he was being tailed by some people. The Hong Kong police then offered him protection.
The delegation, led by the Secretary for Justice, Rimsky Yuen, and the Secretary for Security, Lai Tung-kwok, flew to Beijing on Tuesday morning to hold talks about the cross-border notification mechanism under which mainland authorities must notify the Hong Kong government about the detention of its residents on the mainland.
It followed allegations that Lam and four of his colleagues were kidnapped by mainland security agents and taken to the mainland for selling books critical of mainland leaders.
But after its arrival in Beijing, the delegation was told that Lam was allowed to return to the territory under strict bail conditions and he has breached all of them. The ministry also released a video showing Lam in detention and confessing, but being treated well.
The delegation was also told that the special taskforce investigating the case of the booksellers was set up under the Ningbo's Public Security Bureau. Lam had said the taskforce was under the central government.
The statement released by Beijing officials also detailed the alleged crimes Lam and the others were involved in. It said Lam had admitted to unlawful business operations and that he and another man had used a mainland bank account to collect more than 400,000 yuan by selling 368 banned books.
Beijing's minister of public security, Guo Shengkun, told the Hong Kong delegation that the central government attaches great importance to the notification mechanism.
He said the meeting between them was arranged at short notice because of the need to maintain stability and prosperity in both places.
Lam and four of his colleagues linked to the bookstore had disppeared last year. After missing for weeks, all of them appeared on the mainland.