Sun Hung Kai Properties co-chairmen Thomas and Raymond Kwok were among five people charged under anti-graft laws and will appear in court later Friday, public broadcaster RTHK reported.

Former 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. media reports said.

Sun Hung Kai was suspended from trading 18 minutes after the market opened, pending the release of a potentially price sensitive announcement, it said in a filing to the stock exchange.

The Independent Commission Against Corruption (ICAC) and Sun Hung Kai refused to confirm the reports. No details of the allegations have been made public.

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.

They appeared at the ICAC office earlier Friday before news of the charges broke. Each of them has denied any wrongdoing.

The Kwoks are among Hong Kong's richest men and Sun Hung Kai is the city's biggest property developer by market capitalisation, having built some of the southern Chinese territory's biggest harbourside landmarks.

Hui reportedly worked as a consultant for Sun Hung Kai, and is the most senior official ever arrested by the graft watchdog.