The suicide of a China Securities Regulatory Commission official last weekend, only revealed by a mainland news website yesterday, is likely to trigger a new round of suspicions surrounding the controversial stock market watchdog. Tang Hongwu, a division chief with the commission's market supervision department, killed himself by jumping off a building in Beijing, according to two CSRC officials. The reason for Tang's suicide was unknown, with the officials saying they were told that it was due to personal reasons. But they added that a heavy workload could be part of the reason that caused Tang to take his own life. They said Tang was not under investigation for any wrongdoing. Tang, in his late forties, was not a senior CSRC official. The role of the market supervision department is to co-ordinate with the Shanghai and Shenzhen stock exchanges to spot and investigate suspicious trades. The CSRC stepped up oversight of market irregularities last year amid mounting public anger over its slow pace in dealing with insider trading. The securities regulator has often been blamed for the mainland's roller-coaster stock markets, where millions of retail investors have lost money. The poor job it has done in cracking down on insider dealing has long been a major source of irritation among investors. The CSRC launched a high-profile nationwide campaign last year, investigating nearly all the mutual funds and brokerages in an attempt to uncover the so-called rat traders - those who use friends' or relatives' accounts to trade shares for their own benefit by taking advantage of inside information. Only a few unethical fund managers have been uncovered so far, leading investors to doubt the efficiency of the campaign. Insider trading is believed to be widespread on the mainland. CSRC chairman Shang Fulin says the regulator is committed to eradicating insider trading to protect the interests of small investors. Unable to say exactly what role Tang played in the campaign, the CSRC officials said he was often on business trips and often worked overtime. The top regulators were in panic, the officials said, because Tang's suicide would probably spark new rumours about the CSRC, which has often been linked to corruption and scandals in false market speculation. In April, Wang Yi , a former vice-chairman of the CSRC, was given a suspended death sentence for accepting about 12 million yuan (HK$13.93 million) in bribes.