A Chinese billionaire has been abducted in Hong Kong by mainland agents, according to reports Tuesday, triggering more concerns over security in the city after the disappearance of five booksellers.

Financier Xiao Jianhua, founder of Beijing-based Tomorrow Group, was staying long-term at Hong Kong’s luxury Four Seasons hotel, according to reports in overseas Chinese-language media.

Xiao Jianhua. Photo: Apple Daily.

Xiao, who is usually looked after by a group of female bodyguards, was led away from an apartment at the hotel by Chinese security agents, the Financial Times reported, citing a person familiar with the investigation.

It is unclear why Xiao may have been targeted, but it will add to fears that Chinese authorities are increasingly interfering in semi-autonomous Hong Kong.

It is against Hong Kong’s constitution for mainland agents to operate in the territory.

But after the disappearance of five city booksellers in 2015, there were widespread accusations those restrictions had been breached as one of the men, Lee Bo, went missing from Hong Kong.

All five were involved in publishing salacious titles about the Chinese leadership and resurfaced on the mainland.

Hong Kong police confirmed they had received a “request for assistance” concerning a mainland citizen on Saturday when asked about Xiao’s case.

Hong Kong police. File photo: HKFP.

On Sunday, a family member requested the report be withdrawn, saying the person had contacted them and was safe, a police statement said. It added the person had entered the mainland through a Hong Kong boundary control point.

Tomorrow Group posted a message on its WeChat account Monday, purportedly from Xiao, saying he was taking a break because he was ill. It has since been removed.

“Regarding the reports on me in recent days, I have to say that I, Xiao Jianhua, have been recovering from a sickness outside the country,” the message said.

“Currently everything is fine,” it added, saying the company was running “normally”.

Xiao is reported to have come to Hong Kong in 2014, two years after Chinese President Xi Jinping started a much-publicised anti-corruption drive.

He has denied that he was ever the target of an investigation.

Chinese-language news site Boxun said Xiao had been tipped off that a special investigative unit was about to abduct him when he was still in mainland China.

Hong Kong’s Apple Daily said Tuesday that Xiao had been taken over the border between Hong Kong and mainland China with his wife, who then returned and reported the case to police and media.

She then said Xiao had contacted her and did not want to exaggerate the incident, according to the report.