Bribes of up to US$1 trillion change hands worldwide each year, a World Bank Institute official told a conference of local and overseas graft fighters yesterday. Daniel Kaufmann, director of global programmes at the institute, said such corruption constituted a tax on investment and reduced a country's competitiveness. Mr Kaufmann was speaking at an Independent Commission Against Corruption symposium at the Convention and Exhibition Centre on corporate corruption. Another speaker was Ye Feng, director-general of China's International Judicial Co-operation Department, who said 41,447 Chinese government employees were investigated for bribery and embezzlement last year, and 30,205 prosecuted. In Hong Kong, more than half of the cases investigated by the ICAC are in the private sector. ICAC commissioner Raymond Wong Hong-chiu said the commission would contact all companies as soon as they list in Hong Kong, to prevent listing fraud, and would double the number of officers dedicated to investigating financial fraud. Chief Executive Donald Tsang Yam-kuen, who gave the opening address, said: 'The recent failures of corporate giants around the world have been a reminder for us all that we must fortify our guard against corporate corruption and fraud.' One of the corporate giants Mr Tsang was referring to was Enron, which was involved in one of the world's biggest financial fraud cases. Michael Anderson, the FBI special agent in Houston, Texas, who supervised the investigation into the Enron case from December 2001, was among the speakers at the symposium. Testimony ended yesterday in the US in the fraud and conspiracy trial of Enron founder Kenneth Lay and former chief executive Jeffrey Skilling.