Shanghai shares open down more than 4% after plunge

China's benchmark Shanghai stock index slumped 4.09 percent at the open on Tuesday, despite a renewed government vow to support the market following the biggest fall in eight years a day earlier.

The Shanghai Composite Index plunged 8.48 percent on Monday, the biggest fall since February 27, 2007, despite a broad-based government effort to shore up prices following a weeks-long rout.

The benchmark narrowed some of the losses in morning trade Tuesday and was down 2.12 percent, or 78.88 points, to 3,646.68 later.

The Shenzhen Composite Index, which tracks stocks on China's second exchange, was down 3.52 percent, or 75.93 points, to 2,084.16.

The falls came despite comments by the market regulator, the China Securities Regulatory Commission (CSRC), that it would continue to "stabilise" the market.

The state-backed China Securities Finance Corp., tasked with stabilising the market, would continue to increase its share holdings, the CSRC said in a statement late Monday.

"It's a normal correction of the market since it rose too much before," Zhang Yanbing, an analyst at Zheshang Securities, told AFP.

He added it would take some time for trading to become less volatile.

"In the future, the market will gradually rise and stabilise and finally return to a normal state," he said.

The government intervened after the market plunged 30 percent in just three weeks from mid-June, having risen more than 150 percent in the previous 12 months.

Early efforts failed to change sentiment, until the government banned shareholders with more than five percent stakes from selling stock and launched a police crackdown on short selling.

The market rallied for six sessions until Friday, when an independent survey of manufacturing activity hit a 15-month low in July.