BEIJING (Reuters) - China confirmed on Tuesday that it had detained Swedish citizen and Hong Kong-based bookseller Gui Minhai, after his daughter said Chinese police had seized him from a train last month.

Gui was abducted in Thailand while on holiday in 2015, one of five Hong Kong booksellers who went missing that year and later appeared in mainland Chinese custody. The four others have returned to Hong Kong.

Hong Kong, a former British colony, returned to Chinese rule in 1997 with a guarantee of wide-ranging freedoms, including freedom of speech, but critics accuse Communist Party rulers in Beijing of creeping interference in the city’s affairs.

Gui’s daughter, Angela Gui, said in January that her father was taken from a Beijing-bound train while in the company of two Swedish diplomats who were escorting him to seek medical attention for a neurological disorder.

“Gui Minhai broke Chinese law and has already been subjected to criminal coercive measures in accordance with the law by relevant Chinese authorities,” Chinese foreign ministry spokesman Geng Shuang told a regular briefing.

The term “coercive measures” generally refers to detention in China.

Swedish Foreign Minister Margot Wallström said in a statement on Monday that Gui’s detention was a “very serious matter” and that China’s “brutal” intervention in Sweden’s attempts to assist Gui, who Chinese authorities had said had been freed, represented a contravention of international rules on consular support.

“We demand that our citizen be given the opportunity to meet Swedish diplomatic and medical staff, and that he be released so that he can be reunited with his daughter and family.”

Asked about the statement, ministry spokesman Geng said that China could not accept such “irresponsible” statements from Sweden.

“Although Gui Minhai is a Swedish citizen, the case he is suspected of must be handled in accordance with Chinese law,” he said.

Sweden should understand the serious nature of the case and the “disgraceful” role played by certain Swedish people, Geng said, without giving details.

Rights group Amnesty International said China’s claims about Gui were “ludicrous”.

“This is a brazen and outrageous move by the Chinese authorities. They have yet to provide adequate explanation as to why they took Gui Minhai away while he was traveling with Swedish diplomats. Gui Minhai must be released,” said William Nee, China researcher at Amnesty International.

China’s foreign ministry had previously said that Gui, who published books on the personal lives of Chinese Communist Party leaders, was released in October last year after serving a sentence for a traffic offense in 2003.