Confronted with Lam’s claim that he had been kidnapped by agents from the mainland’s secretive central investigation team while crossing the border to Shenzhen last October, the foreign ministry stressed that Beijing was determined to keep Hong Kong’s ­governing “one country, two systems” formula in place.

“Lam Wing-kee is a Chinese citizen, and he has violated China’s laws on the mainland. Related authorities in China are authorised to handle the case in accordance with the law,” foreign ministry spokeswoman Hua Chunying said on Friday.

On Lam’s claims that his associate, Lee Po, told him he was also kidnapped from Hong Kong in December last year, Hua said Lee had already responded himself, referring to his denial.

On Thursday, Lam described in detail how he was taken away, blindfolded and handcuffed last ­October. He said he decided to risk his personal safety and speak out because Hong Kong’s autonomy had been trampled upon.

Pan-democratic lawmakers were further ­incensed by Beijing’s response ­yesterday.

“It was not a problem about law. Lam was embroiled in a political conflict,” the Democratic Party’s Albert Ho Chun-yan, who has been helping Lam, said. “And Lam has only printed, sold and mailed the books from Hong Kong. On what legal basis was he detained on the mainland?”

The story took another dramatic twist on Friday when Lee denied telling Lam he had been kidnapped and forced to hand over lists of customers to whom they had sold books banned on the mainland for content critical of China’s leaders.

“I have never used the computer at Causeway Bay Books. I have never printed out any lists of customers, let alone passed any lists to the mainland police,” Lee wrote on his Facebook page.

He insisted that when he met Lam on Thursday, he had not mentioned how he ended up on the mainland after vanishing from Hong Kong.

“I didn’t say I went to the mainland involuntarily or anything like that,” he said. “I was assisting the ­investigation by Ningbo’s public security bureau. I have never heard of the central investigation team.”

Five men associated with Causeway Bay Books and Mighty Current publishing house disappeared one after another, starting in October last year. Gui Minhai vanished first from Pattaya, Thailand in October. Lam, Cheung Chi-ping and Lui Por went missing while on the mainland. Lee disappeared from Hong Kong in December.

All five eventually surfaced on the mainland, claiming they had gone there voluntarily. Gui was accused of ordering his associates, including Lam, to deliver about 4,000 banned books across the border since October 2014.

“We have always attached great importance to the personal safety of Hong Kong residents,” financial secretary Tsang said when asked whether Lee would be safe and protected after his revelations. “We will continue to protect Hong Kong residents’ rights and their freedom in accordance with the law,” Tsang said.

Secretary for Justice Rimsky Yuen Kwok-keung noted that Lam’s story had changed after his initial statement to police upon his return to Hong Kong that he had not been kidnapped or forcibly detained.

“Obviously there’s a need for the police to follow up ... so as to get more information and to find out exactly what has happened before we can decide, or we can even suggest what had been done or what should be done,” he said.

Yuen said if a person was in the mainland’s jurisdiction, then he was expected to comply with and was subject to mainland law. But if that person was in the city, he was entitled to all the legal protections conferred by Hong Kong laws, including those under the Basic Law and the Bill of Rights Ordinance.

A protest demanding answers will be held on Saturday.

Additional reporting by Jasmine Siu and Danny Lee