(CNN) A Chinese billionaire with Canadian citizenship has been seized from his apartment at the Four Seasons hotel in Hong Kong and taken to mainland China, a source familiar with the situation told CNN Wednesday.

Hong Kong police said they were investigating the disappearance of Xiao Jianhua, who was reported missing Friday. Police added that they had received a request Saturday from a family member to drop the case.

"We are still investigating and have reached out to the mainland authorities concerned," the statement sent to CNN Tuesday said.

Xiao is one of China's richest men and controls theTomorrow Group, a massive holding company with stakes in banks, insurers and property developers. According to Hurun , which analyzes Chinese wealth, Xiao is 46 and has a net worth of $6 billion.

Chinese businessman Xiao Jianhua speaking at the naming ceremony of the Tianshi Institute of Robotics Chinese University of Hong Kong, in April 2016.

Similar pattern?

Xiao's disappearance adds to fears that freedoms guaranteed under the "one country, two systems" policy agreed to as part of Britain's 1997 handover of Hong Kong are being eroded as Beijing asserts more control over the city.

His case has drawn comparisons with Lee Bo, a bookseller and British passport holder that disappeared from Hong Kong in late 2015 and later turned up in Chinese custody.

Lee's removal, which came after the disappearance of four of his colleagues , sparked outrage in Hong Kong and internationally over fears he was taken against his will by Chinese law enforcement agents, who aren't permitted to act in the self-governing city.

Xiao Jianhua (R) giving a donation check to Chinese University of Hong Kong President Professor Joseph Sung in April 2016.

One of the booksellers, Swedish citizen Gui Minhai, remains in detention 15 months after he was taken from Thailand.

Front-page denial

The person familiar with the situation told CNN that there was a small scuffle between two dozen security officials and Xiao's own security detail, which usually numbers about eight bodyguards per shift.

The source, who wanted to remain anonymous because of the politically sensitive nature of the case, said Xiao had close connections to some of China's most powerful families.

In a front-page ad published in Hong Kong's Mingpao newpaper Wednesday, Xiao appeared to deny he had been kidnapped.

The statement in Chinese, which had Xiao's name printed at the bottom, said that he was "recuperating overseas" and hoped to meet with media once he had recovered.

"I'm a patriotic overseas Chinese and I've always loved the party and the country," it said. The statement added that he was a Canadian citizen entitled to consular assistance and a permanent Hong Kong resident.

A front-page ad published in a Hong Kong newspaper Wednesday with Xiao Jianhua's name printed at the bottom denied he'd been kidnapped.

Mingpao said they couldn't disclose who bought the unusual ad, which according to the newspaper's advertising rate card would have cost $36,500.

Other high-profile businesspeople detained in China have been pressed to release messages insisting that everything is fine.

The newspaper statement was similar to a post on the Tomorrow Group's WeChat account -- a social network and messaging app that's massively popular in China. The post has since been deleted.

The Four Seasons, which occupies a 45-story skyscraper that commands spectacular views of Hong Kong's harbor, said it was cooperating with the police investigation but declined to comment further.

A general view shows the Four Seasons Hotel building in Hong Kong on February 1, 2017.

The Canadian Consulate said it was aware of the reports and officials were "in contact with the authorities to gather additional information and provide assistance."

"In order to protect the privacy of the individual concerned, further details on this case cannot be released."

China's Ministry of Foreign Affairs and Public Security Ministry didn't respond to a request for comment.

Who is he?

Born in China, Xiao also held a diplomatic passport from Antigua and Barbuda, where he was an ambassador at large, according to a statement on the Antigua government website. The country's foreign ministry didn't immediately respond to a request for comment.

According to the Financial Times, Xiao was a financier with links to the family of Chinese President Xi Jinping.

He was one of a number of Chinese tycoons who had moved to Hong Kong and taken up residence in private apartments at the 5-star Four Seasons hotel during Xi's crackdown on corporate excess, the paper said.

A 2014 profile in the New York Times said Xiao was often surrounded by aides and retained a number of female body guards "who even wipe the sweat from his brow."

Born in a poor mountain village, Xiao passed the highly competitive college entrance exam at 14 and attended Peking University, China's most prestigious, it added.