China's benchmark Shanghai stock index opened down 2.13 percent on Thursday, extending losses from a day earlier, despite more government moves to avert a market collapse.

The benchmark Shanghai Composite Index lost 74.74 points to 3,432.45 while the Shenzhen Composite Index, which tracks stocks on China's second exchange, fell 1.05 percent, or 19.76 points, to 1,864.69.