Regulators, worried about by China's red-hot stock market fever, are taking a new measure to cool it by banning listed firms, flush with new share sale proceeds, from investing it in securities.

The listed companies are also banned from buying derivatives and convertible bonds with the proceeds, the China Securities Regulatory Commission, China's stock market watchdog, said in a statement seen on its website on Tuesday.

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The regulator said it will monitor companies more closely. Prime Minister Wen Jiabao said at a press conference in Beijing on Friday that his administration wants to see to a healthy stock market in China. He promised closer look into companies' books.

"Companies should not directly or indirectly use newly acquired funds to buy stocks or derivatives or convertible company bonds," the regulator said in a statement. Firms must use the proceeds from share sales for the intended purposes, it said.

If the enterprises intend to spend more than 10 percent of the raised capital on items that the share sale was not originally aimed at funding, they must get board approval and arrange an online shareholder vote, it said.

"Regulators are concerned that proceeds are fueling the stock market frenzy," said a securities fund manager in Shanghai.

Beijing wants to curb speculation in the real estate and stock markets to break boom-bust cycles fueled by 33.5 trillion yuan (US$4.3 trillion) of household and corporate deposits. The speculative activity has driven equity prices up by around 150 percent in the last 15 months.

China's central bank, the People's Bank of China, announced over the weekend that it was raising interest rates by 27 basic points, but it has failed to damp the feverish stock market, which rose both Monday and Tuesday.

The frenzy has prompted officials to repeatedly warn that a major bubble had formed and that investors, especially inexperienced retail punters, stood to lose everything if the markets crashed.

On February 27, investors got a strong taste of the kind of volatility that worries regulators when China's key Shanghai index slumped nearly nine percent in its steepest one-day fall in 10 years. Prices have since recovered and surged to new record highs.

In another step aimed at dampening the frenzy, banking regulators have moved to investigate a sudden spike in consumer loans believed to be fuelling the market speculation.

The China Banking Regulatory Commission ordered in January that commercial banks recall property loans suspected of being used instead to speculate in the nation's red-hot stock markets.