Beijing - Mainland China's two stock markets soared Thursday after an official assured investors that government regulators would act to shore up stock prices.

The key Shanghai Composite Index, which tracks shares traded in local and foreign currencies, gained 4.79 per cent, or 130.05 points, to close at 2,845.02.

The smaller Shenzhen Composite Index also gained following two days of marginal rises after stocks had plummeted by about 7 per cent on Monday.

Several newspapers on Thursday quoted Liu Xinhua, vice chairman of the China Securities Regulatory Commission, as saying that regulators would take measures to "promote the steady and healthy development of the market."  (dpa)