Two billionaire brothers who run Hong Kong's top property developer said Tuesday they're innocent of the suspected corruption they were arrested for last week in the city's biggest graft probe in decades.

Raymond and Thomas Kwok, joint chairmen and managing directors of Sun Hung Kai Properties Ltd., were arrested briefly Thursday by the Independent Commission Against Corruption.

"I want to confirm to everyone that I myself haven't done anything wrong and I believe Thomas Kwok hasn't done anything wrong either," said Raymond Kwok. "I expect the investigation will prove we're innocent."

The pair were arrested for alleged bribery, along with an ex-government official whom local news reports have identified as a former chief secretary _ the No. 2 job in the government.

They have not yet been formally charged as the investigation continues in the semiautonomous Chinese territory.

The Kwok family is one of Asia's richest, with a net worth of $18.3 billion, according to Forbes.

Sun Hung Kai, Hong Kong's biggest developer by market value, has built some of Hong Kong's most recognizable buildings, including the 118-story International Commerce Center in Kowloon, the city's tallest.

Thomas Kwok told reporters that it would be "business as usual" at Sun Hung Kai, which said last week that the two would continue in their roles.

The arrests shocked Hong Kong and are likely to add to growing public mistrust of the city's tycoons. Fed up with a growing rich-poor gap driven by soaring property prices, ordinary residents are growing increasingly worried that the city's billionaires, many of whom have made their fortunes from real estate, have too much influence on the government. It controls all the land in the compact, densely populated city.

Five people, including another Sun Hung Kai executive, were arrested earlier.

A third brother, Walter Kwok, was ousted as chairman and chief executive in 2008 following a bitter legal feud in which he accused Raymond and Thomas of plotting to remove him by portraying him as mentally ill.