Since the beginning of the year, turnover on the two Chinese bourses has averaged 100 billion yuan (US$12.8 billion) every trading day, triple the average daily transaction volume for 2006. The figure soared to more than 150 billion yuan on Monday.

At the Shenzhen marketing center of Guosen Securities, the business hall was packed out, with investors queuing in front of counters.

One investor complained, "There are more people here than in banks. I have been waiting for more than one hour, but it's still not my turn."

Some newcomers, unaware of risks of the stock markets, require explanations from brokers.

Sources with the marketing center said hundreds of new accounts were opened in each of the past few days.

Another securities firm, China Merchant Securities, has opened nearly 20,000 new stock accounts since the beginning of 2007, company officials said.

However, the volume of new accounts has caused bottlenecks in its stock trading systems and the overload has incurred losses for investors.

Industry insiders pointed out that insufficient investment in trading systems and a lack of awareness of risks accounted for the trouble.

Last year witnessed a string of incidents resulting from inadequate administration of trading systems.

On January 7, 2006, the databank broke down at a securities firm, breaking off business in 40 outlets of the company. Operations resumed two hours later.

On March 29 and 30, another securities firm fell victim to online fraud, which caused losses to 11 stock accounts.

On April 12, repeated contracts occurred at a third securities firm, which led to overdrafts at 36 stock accounts, involving more than 570,000 yuan.

Industry regulators warned that securities firms should adequately upgrade and supervise trading systems and ensure sufficient investment.