A corruption trial involving Hong Kong's former chief secretary Rafael Hui and two of the city's richest men Thomas Kwok and Raymond Kwok opened Thursday.

Hui, 66, the most senior official ever charged of graft in Hong Kong, is accused of accepting 34 million HK dollars (about 4.39 million U.S. dollars) from the Kwok brothers, [Hong Kong Company Formation]who jointly chair one the world's major developers Sun Hung Kai Properties, in exchange of land sales information.

Hui and the Kwok brothers were arrested by the city's graft- buster Independent Commission Against Corruption in March 2012. The three were among five people charged with eight offences including misconduct in public office and furnishing false information. All pleaded not guilty.

The trial is expected to last for 70 days, with evidence of more than 80 prosecution witnesses.