China's benchmark Shanghai stock index opened down 3.21 percent on Tuesday, wiping out short-lived gains from a day earlier after the government unveiled a new package of measures to boost the slumping market.

The Shanghai Composite Index dropped 121.13 points to 3,654.78. The Shenzhen Composite Index, which tracks stocks on China's second exchange, lost 3.50 percent, or 71.47 points, to 1,970.38.