[BEIJING] Only a year ago he was hailed as one of the boldest dealmakers in China.

But on Wednesday, with scant explanation, Wu Xiaohui was said to be unable to perform his duties as chairman of Anbang Insurance Group Co. In a terse statement sent to reporters around 2am Beijing time, Anbang said only that Mr Wu - who had spent more than a decade transforming the company into a global juggernaut - was no longer able to serve in his post because of personal reasons. Other senior executives will carry out his responsibilities, the Beijing-based company said.

The development added another layer of intrigue to the story of Anbang, whose overseas acquisition spree has slowed in recent months amid increased scrutiny at home and abroad. China's central bank was said to look into suspected breaches of anti-money laundering rules at the insurer late last year, while authorities temporarily banned Anbang's life insurance unit from selling new products in May. High-profile bids for American hotels, insurance assets and a Manhattan office tower owned by the family of US presidential adviser Jared Kushner have all fallen through over the past 18 months.

"It looks very unlikely that Anbang will be able to continue its overseas buying spree," said Grace Zhou, a Hong Kong-based analyst at ICBCInternational. "Its business model is no longer viable given tightened regulatory scrutiny," Ms Zhou said, adding that the latest shock to the firm's reputation could drive policy surrenders and make it harder for Anbang to tap international financing.

The exact nature of Mr Wu's role in any government investigation has become the subject of widespread speculation. Before Anbang's statement, Caijing Magazine, citing unidentified sources, reported that Mr Wu had been taken away by Chinese authorities on June 9. The article, which said it was unclear whether Mr Wu was assisting with a government investigation, was later deleted from the magazine's website.

Caijing didn't answer calls and emails requesting comment, while Anbang referred to its statement when asked to comment on the Caijing report. The company on June 2 denied a Financial Times report that said Mr Wu was barred by Chinese authorities from leaving the country.

It wouldn't be the first time a Chinese tycoon has allegedly fallen afoul of Chinese authorities. Prominent financier Xiao Jianhua was taken by agents from a Hong Kong hotel earlier this year and presumed to have been brought back to China, according to local media reports. Executives of a company controlled by tycoon Guo Wengui stood trial this month on charges of loan and foreign exchange fraud, the state-owned Xinhua News Agency reported, after Chinese authorities issued a request to Interpol for Guo's arrest in April.

Anbang's story begins in 2004, when it was founded as a property-and casualty-insurer selling auto policies. While the firm was little-known to the wider world back then, Anbang had some powerful backers inside China. The company's early shareholders included state-owned behemoths SAIC Motor Corp and China Petroleum & Chemical Corp, known as Sinopec.

Anbang added a life unit in 2010 and turbocharged its expansion in 2014 by selling single-premium, high-yield policies - many of which could be redeemed in two years at a profit. With names like Anbang Longevity Sure Win No 1, the products offered returns well above benchmark deposit rates and have proven popular with mom-and-pop investors. Anbang now has almost 2 trillion yuan (S$406.7 billion) of assets and more than 30,000 employees, according to its website.

Mr Wu first turned heads outside China when Anbang offered to buy New York's iconic Waldorf Astoria hotel in October 2014. Chinese media likened his approach - using insurance income to fund wider ambitions - to the model honed by Berkshire Hathaway Inc's Warren Buffett. The Waldorf acquisition was followed in short order by bids for six luxury resorts in the US, including the landmark Hotel del Coronado near San Diego, California. Anbang's targets have also included the Belgian banking operations of Delta Lloyd NV, South Korean insurer Tongyan Life Insurance Co and Starwood Hotels & Resorts Worldwide Inc.

The US$14 billion Starwood bid, which Anbang abruptly dropped in early 2016, was the first in a series of high-profile deal failures. Later that year, Anbang called off an agreement to buy a landmark Southern California hotel from Blackstone Group LP after US national security officials expressed concern over the property's proximity to a naval base. The insurer's offer to acquire US-based Fidelity & Guaranty Life fell through in April after it struggled to win regulatory approval.

In March, Anbang canceled talks with Kushner Cos, which is owned by the family of US President Donald Trump's son-in-law. The negotiations to redevelop 666 5th Avenue had came under scrutiny from Democratic lawmakers, who cited ethics concerns about the Chinese firm's potential investment.

Some of the headwinds facing Anbang aren't unique to the company. China's insurance regulators have embarked on an industrywide crackdown this year, seeking to curtail sales of risky products and restrict acquisitions of listed firms. The volume of outbound deals from China has plunged across the board as the government tightened capital controls to support the yuan.

Yet in several cases, Anbang has been singled out by authorities. The People's Bank of China looked into suspected breaches of anti-money laundering regulations by the insurer in late 2016, according to people with knowledge of the matter. It wasn't clear if that investigation identified any wrongdoing. The central bank didn't reply to a fax seeking comment and Anbang declined to comment.

Some Chinese government-linked business associations that promote trade and investment were told by authorities at the end of 2016 that they shouldn't enter into new partnerships with Anbang and should terminate existing relationships, according to people with direct knowledge of the situation.

Last month, China's top insurance regulator slapped a three-month ban on new products at Anbang's life unit after saying one of its policies circumvented rules on short- and medium-term policies and disrupted market order.

Anbang has also faced questions about its shareholding structure before a proposed initial public offering of the company's life insurance assets in Hong Kong. Morgan Stanley decided not to pitch for a role on the deal amid concerns over whether the company would provide enough details on its ultimate ownership, according to people with knowledge of the matter.

Anbang is controlled by a group of companies owned by about 100 people with ties to Mr Wu, many of them hailing from his home county of Pingyang on the eastern Chinese coast, the New York Times reported last year. At least 35 of Anbang's corporate shareholders can trace all or part of their ownership to relatives of Mr Wu or his wife, according to the report.

BLOOMBERG