HONG KONG - The billionaire brothers of Hong Kong property developer Sun Hung Kai Properties returned to the city's Independent Commission Against Corruption on Tuesday morning, according to Cable Television.

It was the second time in two weeks that the brothers have been called in to Hong Kong's anti-corruption agency.

The investigation into Raymond and Thomas Kwok, co-chairmen of Sun Hung Kai Properties Ltd, is the biggest case launched by Hong Kong's Independent Commission Against Corruption (ICAC) since it was set up in 1974 to root out graft.