"Mature investors should have realized gradual corrections from irrational levels are better than a sudden burst," said Leo Gao, who helps manage the equivalent of US$2.3 billion with APS Asset Management Ltd. in Shanghai, Bloomberg reported.

"The government is right to tighten the regulations without intervening in the market," Gao said.

The Shanghai and Shenzhen 300 Index, which tracks yuan-denominated A shares listed on China's two exchanges, plunged 182.65, or 7.2 percent, to 2369.24 at 2:48pm local time, cutting this month's gain to 16 percent. That's the biggest one-day drop since the measure was introduced in April 2005.

China Vanke, the nation's biggest publicly traded property developer, fell 1.67 yuan, or 9.9 percent, to 15.23. China Merchants Bank, the third-largest lender, lost 1.30 yuan (17 US cents), or 7.1 percent, to 17.15. Citic Securities Co., the country's biggest brokerage, lost 3.48 yuan, or 9.2 percent, to 34.19.

Only 30 percent of companies on the Shanghai Stock Exchange are good to invest in by Western standards, and investors in 70 percent of the companies on the exchange will probably lose money, Cheng, vice chairman of the National People's Congress, said yesterday at a conference in Dubai.

The Financial Times, which sponsored the conference, quoted Cheng saying China's stock market showed signs of a "bubble."

"Every investor thinks they can win," the paper quoted him saying. "But many will end up losing."

China's banking regulator ordered banks to make proper checks and stop lending to companies and individuals that use the money for stock investments, the Shanghai Securities News reported on January 27.

Commercial banks should guard against those who apply for loans in the name of purchasing consumer goods, or other legal uses, but in reality use them to buy stocks, the newspaper said, citing the China Banking Regulatory Commission.

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