BEIJING (AP) — China said Monday that a Hong Kong-based Swedish man who sold gossipy books about Chinese leaders is under detention on suspicion of leaking state secrets, and rebuked Stockholm for demanding his release.

Foreign ministry spokesman Geng Shuang said Gui Minhai had "violated Chinese laws and thus must be dealt with in accordance with Chinese laws."

"The Swedish side's repeated demands that China release him is a crude and unjustifiable interference into China's judicial sovereignty. We have lodged multiple solemn representations with the Swedish side over this matter," Geng said.

Gui, 53, was taken off a train by police on Jan. 20 while in the presence of two Swedish diplomats with whom he was traveling to Beijing. Sweden said its officials were taking him to seek medical treatment.

On Sunday, police in the eastern city of Ningbo said that Gui was being held in the city jail and that they had evidence to back up their accusations that he leaked state secrets and intelligence to foreigners. No details about the charges were given.

Gui told pro-Beijing media outlets Saturday that he never wished to leave China and that Sweden was using his case to "create trouble" for China's government.

"Looking back, I might have become Sweden's chess piece. I broke the law again under their instigation," Gui was quoted as saying by Hong Kong's South China Morning Post newspaper. "My wonderful life has been ruined and I would never trust the Swedish ever again."

The statement from Gui, who spoke in a detention facility flanked by police, was immediately denounced by rights activists as coerced. In putting Gui before the press, Chinese state security appeared to be responding to Swedish Foreign Minister Margot Wallstrom, who last Monday sharply questioned the rule of law in China and blasted Beijing's "brutal" treatment of Gui after weeks of relatively mild pleas for his release.

Gui went missing in 2015 from his seaside home in Thailand, turning up months later on Chinese television saying he had turned himself in for an alleged 2003 drunk driving accident in which a female college student was killed.

Several of Gui's colleagues from his Hong Kong publishing house also went missing in quick succession, sparking suspicions that mainland security forces were seeking to snuff out independent voices in the semi-autonomous city.

Gui was released in October after completing his two-year sentence, but had committed to remaining in Ningbo until an investigation was completed into charges of running a business illegally, the Ningbo police said in its statement faxed to The Associated Press. It gave no details about the state of that investigation but said Gui's rights were being preserved as he faced the new charges.

Gui's overseas friends and family, including his daughter Angela, have said the charges are bogus and that Gui was keen to leave China for Europe.