China's benchmark Shanghai stock index surged more than five percent in afternoon trading on Thursday, extending gains after the government issued more policies to halt a market slide, dealers said.

The benchmark Shanghai Composite Index jumped 5.30 percent, or 185.95 points, to 3,693.14 after falling as much as 3.81 percent in the morning. The Shenzhen Composite Index, which tracks stocks on China's second exchange, added 3.67 percent, or 69.22 points, to 1,953.67.