Shanghai -- China's stock markets risk disruptions from record turnover and growing volatility, the Shanghai Stock Exchange has warned in the latest sign regulators are alarmed over the market's recent surges.

"We must pay close attention to risks in the market, chiefly whether the technology system and trading platform can handle such large trading volumes," the head of the exchange, Geng Liang, said in a statement seen Tuesday.

Trading volumes in Shanghai have soared since the beginning of the year, with turnover in the first two weeks at 1.2 trillion yuan (US$154 billion) compared with 6 trillion yuan for all of 2006 (US$772 billion), said the statement, posted on the Web site of the exchange.

And last year's figure was triple the turnover in 2005, it said.

Trading volumes have jumped to record highs since the beginning of the year as investors rush into the market after seeing the benchmark Shanghai index surged a stunning 134 percent last year.

The statement was issued following a recent meeting convened by top executives of the exchange. It noted the need for brokerages to upgrade technology and improve technical expertise.

Both Shanghai and the smaller exchange in Shenzhen have ordered brokerages to upgrade online trading systems to prevent disruptions, state media reported.

The alert follows public calls for caution by other regulators. Authorities have stopped registering new mutual funds, have postponed the launch of stock index futures, and warned against using funds borrowed against illegal use of bank loans for stock trading.

The China Banking Regulatory Commission plans to investigate loans at all commercial banks following next month's Lunar New Year holiday, which begins February 18, the China Securities Journal reported Tuesday.

It said the investigations would focus on property loans, which are often used for other purposes. Bank officials in charge of approving such loans would be harshly punished, it said without giving specifics.

Problems with online trading platforms already have triggered complaints from some investors, local reports said.

Some other regional markets have faced problems with online trading systems. In December 2005, the Tokyo Stock Exchange, Asia's largest, failed to intercept a massive trading error. That followed a separate computer system glitch that forced the bourse to shut down trading for all but 90 minutes on November 1, 2005.