Hong Kong anti-corruption officials early Thursday raided the home of Jimmy Lai, an outspoken mogul whose media empire is often fiercely critical of Beijing.
The swoop comes at a time of growing disquiet in Hong Kong over the erosion of press freedom and perceived influence Beijing holds over the semi-autonomous city.
Lai came under the spotlight recently when documents were leaked to the media alleging he made a series of major donations to pro-democracy lawmakers who are critical of Beijing.
Officers from Hong Kong's Independent Commission Against Corruption (ICAC) visited Lai's luxury mansion shortly after 7:00 am (2300 GMT Wednesday).
"ICAC was here and they're all gone now," Lai told a host of reporters waiting outside his luxury home in the upscale neighbourhood of Ho Man Tin. "There is no further comment."
Trading in shares of Lai's Next Media, publisher of the prominent Apple Daily tabloid known for its anti-Beijing stance, were suspended after they plunged more than three percent following the raid.
In a statement the ICAC said searches were carried out on three residences and an office in the city's de facto parliament -- the Legislative Council -- following allegations a lawmaker had accepted a bribe.
The statement did not name Lai or any others.
However pro-democracy lawmaker and staunch Beijing critic Lee Cheuk-yan told Cable Television News on Thursday that he was visited by anti-corruption officers and said the investigation revolved around donations Lai had made to his party.
Lai has denied any wrongdoing and there are no laws that require the disclosure of political donations in Hong Kong.
- Colourful media tycoon -
Political discontent in Hong Kong is at its highest level in years as fears mount that the freedoms enjoyed in the southern Chinese city are being eroded.
The top committee of China's rubber-stamp legislature is currently meeting in Beijing this week to decide how much of a say Hong Kongers will have in electing their next leader in 2017.
Beijing wants candidates to be vetted by a nominating committee, something pro-democracy activists have vowed to contest with some groups threatening to occupy the city's financial district.
Lai is a flamboyant tycoon whose outspoken criticism of Beijing has angered local and mainland officials as well as media rivals.
His media empire is also known for Next Media Animation, a Taiwan-based company that produces satirical, computer animated news reports that routinely mock powerful figures and often go viral.
Two weeks ago a rival newspaper published a fake obituary for Lai, claiming he had died of AIDS and cancer.
Lai hit back with a caustic video.
"They want me to die? Is it really that easy?" Lai said. "Sorry to disappoint you."
The website of Apple Daily, the tabloid owned by Lai, suffered a blackout for several hours in June in what it described as a large-scale attack launched by sophisticated hackers.
Concerns over press freedom have grown this year following several attacks on Hong Kong media workers. The former editor of a respected liberal newspaper, Kevin Lau, was savagely stabbed in broad daylight in February.
The city was handed back to China by Britain in 1997 under a "one country, two systems" agreement, which allows residents civil liberties not seen on the mainland including free speech and the right to protest.