Anti-corruption officers conducted an early morning raid Thursday on the Hong Kong home of Jimmy Lai, an outspoken mogul whose media empire is often highly critical of Beijing.

Trading in shares of Lai's Next Media, one of the city's major press groups, were suspended following the raid.

The investigation 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.

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."

The commission declined to detail what sparked the raid, saying it would not comment on individual cases.

Lai recently made headlines when documents were leaked to the media alleging he made a series of major donations to pro-democracy lawmakers who are critical of Beijing.

He has denied any wrongdoing and there are no laws that require the disclosure of political donations in Hong Kong.

Pro-democracy lawmaker 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.

Shares in Next Media were trading down more than three percent at HK$0.95 ($0.12) before they were suspended at the company's request.

Lai is a colourful character whose outspoken criticism of Beijing has angered local and mainland officials as well as media rivals.

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, a prominent tabloid newspaper 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.

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.

Beijing has insisted that it will vet candidates before a vote in 2017 for the city's next leader, raising concerns that they will only allow pro-Beijing candidates to run.

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.