A Chinese investor watches the stock trend on the cell phone at a stock brokerage house, Aug 24, 2015.[Asianewsphoto by Liu Junfeng]

Stocks tumble further, dragging the benchmark Shanghai index to its lowest level since March, as policy supports fail to prop up the market.

The Shanghai Composite Index fell to as low as 3,209.55, down 8.5 percent, on Monday. It traded at 3238.37 points as of 10:40 am.

The gauge plunged after sinking 12 percent last week, despite the State Council granting pension funds access to equities for the first time over the weekend.

These funds will be able to invest up to 30 percent of their net assets or 600 billion yuan in total ($97 billion) in the country's stocks, equity funds and balanced funds, according to rules published by the Cabinet.

The outstanding balance for margin trading at Shanghai Stock Exchange dropped for a fourth day by 2.4 percent to 848.6 billion yuan as of Friday, according to data by the bourse.

The Shenzhen Component Index slid 7.2 percent to 11,043.17 as of 10:40 am. The CSI 300 traded at 3,313.52, down 7.7 percent.