The bank reported a nine-month low for its Purchasing Managers Index, to a reading of 48.3 in June, down from 49.2 in May.

Warnings about tightened liquidity in the interbank system, and the government's determination to continue with its prudent monetary policy, have also bruised investor confidence, analysts said.

The CSRC spokesman said the regulator had taken note of the dramatic falls in major stock prices.

"The market is influenced by complicated factors, including the basic economic situation, market liquidity, and the operational and financial conditions of enterprises," he said.

The commission has pledged to tighten regulations on insider trading and financial fraud by improving the basic laws and regulations, to create a fairer market environment for investors.

Central Huijin Investment Ltd, a State-owned investment company, on Thursday confirmed it had increased its holdings in six financial institutions, including the "big four" State-owned commercial banks.

The company said it will increase investment in exchange-traded funds.

Some analysts viewed Huijin's move as a clear determination to shore up the stock market, however, the CSRC downplayed the investments as "just a common action based on the market situation".