Hong Kong tycoon brothers Thomas and Raymond Kwok on Tuesday declared their innocence and sought to calm investors after their arrest last week as part of the city's biggest corruption probe.

The pair's first comments since their arrest over bribery allegations came as their firm Sun Hung Kai Properties placed an advert in all the city's major newspapers warning the media against "unfounded speculation" over the case.

At the news conference Raymond said: "I have not done anything wrong and I believe Thomas has not done anything wrong either. I hope the investigation will prove my innocence."

The Kwoks, two of Hong Kong's richest men and co-chairmen of Sun Hung Kai Properties, the city's biggest property developer by market capitalisation, were detained by the Independent Commission Against Corruption on Thursday.

"This incident definitely will not affect the company's operation and decision-making," Raymond said at the firm's harbourfront headquarters as he looked to reverse a slump in the company's share price totalling 15 percent on Friday and Monday.

The firm's price did edge up two percent Tuesday ahead of the conference.

At the same brief news conference Thomas assured investors that the property giant would continue business as usual, saying: "Let me assure you -- no worries, all is normal at Sun Hung Kai."

He added that the company has a professional team of managers to run things.

"All the projects will continue, we will not slow down," Thomas said.

The pair were arrested late Thursday along with a former top government official, identified by local media as the city government's former Number Two Rafael Hui, a close ally of outgoing Hong Kong leader Donald Tsang.

All three were released on bail after questioning. None has been charged.

The SHK advert hit out at recent reports surrounding the Kwoks' arrest, which it said will "adversely affect" the firm, its share price and the shareholders' interest.

It warned: "The company hereby expressly reserves all its rights to take appropriate action to safeguard its interests and those of its shareholders, if the circumstances so require or warrant."

The ICAC has not released details on the bribery allegations but the arrests have sent shockwaves through the Asian financial hub and raised questions about the cosy ties between its business elite and the government.

The arrests came just days after the city's leadership election where a mainly pro-Beijing electoral committee picked the wealthy property consultant Leung Chun-ying to replace Tsang in July.

Leung has vowed to boost public housing, prompting concerns from the city's influential property developers.

The Kwoks have an estimated family wealth of $18.3 billion, according to Forbes magazine, second only to the city's richest man, the 83-year-old Li Ka-shing, founder of rival developer Cheung Kong Holdings.

Sun Hung Kai has built some of the city's most prominent landmarks including the territory's tallest building, the International Commerce Centre.