Two of Hong Kong's richest tycoons and a former senior official were charged with corruption on Friday in the biggest graft scandal the regional banking hub has seen.

Sun Hung Kai Properties co-chairmen Thomas and Raymond Kwok, two of Asia's wealthiest men, were among five people charged with eight offences related to payments and unsecured loans amounting to HK$34 million ($4.38 million).

Former government chief secretary Rafael Hui was also charged, along with another Sun Hung Kai director, Thomas Chan, and Francis Kwan, former non-executive director of New Environmental Energy Holdings Ltd.

The case has shocked Hong Kong as the Kwoks own some of the city's most iconic real estate and Sun Hung Kai is a blue-chip listed company and the city's biggest property developer by market capitalisation.

Hui, 64, is the most senior official ever arrested by the Independent Commission Against Corruption (ICAC).

The former number two in the semi-autonomous southern Chinese city, he faces eight charges related to misconduct involving rent-free use of luxury apartments and unsecured loans, the ICAC said.

Thomas Kwok, 60, faces two charges of conspiracy to commit misconduct in public office, and his 59-year-old brother Raymond has been charged with three offences including furnishing false information, the ICAC said.

Raymond Kwok conspired to offer Hui annual extensions of an unsecured loan, while Chan and Kwan offered the official a "series of payments" as a "reward" for cooperation, the anti-graft investigators said.

All five suspects appeared in court to hear the charges, before being released on bail -- in the Kwoks' case HK$10 million each. They were not required to enter pleas.

"I believe I have not done anything wrong and that the Hong Kong judiciary system is fair. I will fight the accusations and I hope it will prove my innocence," Raymond Kwok said outside the court.

He said he has relied on yoga to deal with the legal challenge while Thomas Kwok said he will draw on his Christian faith to fight the case, quoting from the Bible saying he believed "light will shine in the darkness".

"I want to encourage people to learn yoga because it can help you to relax and it has helped me to face the challenge in these few months," Raymond Kwok told a news conference later where he appeared with his elder brother.

The Kwok brothers and Hui were arrested in March in a case that has sent shockwaves through the Asian financial centre, where cosy links between wealthy tycoons and officials have long raised suspicion.

A third Kwok brother, Walter, was arrested in May but has not been charged. Each of the Kwoks has denied any wrongdoing.

Shares in Sun Hung Kai were suspended from trading on the Hong Kong stock exchange earlier Friday.

The company, which owns billions of dollars of land and harbourside real estate, has previously said the allegations against its directors would not impact on its business.

Analysts said the case reinforced public suspicion that officials were in the pockets of Beijing-backed business elites, who control everything from ports to telecommunications and even supermarkets.

"Hong Kong has always been ruled by the 'property hegemony'," financial services firm Lyncean Holdings managing director Francis Lun told AFP.

"The property tycoons always call the shots in Hong Kong... I don't think that (the charges) will change anything, the property tycoons will get richer and they virtually own Hong Kong."

While the charges do not relate directly to the new government of Chief Executive Leung Chun-ying, who took office earlier this month, they will fuel popular discontent with a system many see as rigged against ordinary people.

Leung has faced calls for his resignation and a legal challenge to his rule over his failure to declare illegal structures at his home, a sensitive issue in the crowded city of seven million people.

His development minister resigned after less than two weeks in the job on Thursday amid allegations he had abused his government housing allowance in the 1980s, raising questions about whether he was fit to be in the new cabinet.

Former chief executive Donald Tsang ended his term in disgrace in June after admitting to accepting gifts from tycoons in the form of trips on luxury yachts and private jets.