BEIJING - China's national observatory on Thursday issued a blue alert for rainstorms as heavy downpours continue to wreak havoc in vast stretches of the country.

From Thursday to Friday afternoon, heavy rain and rainstorms are expected in the regions of Guangxi, Hunan, Guangdong, Jiangxi, Fujian and Zhejiang, the National Meteorological Center said.

Some areas in Guangxi will see up to 150 mm of rain, the center said, warning that regions of Gansu, Hebei, Shandong, Liaoning, Yunnan as well as the Tibet Autonomous Region will experience downpours with up to 70 mm of hourly rainfall.

China has a four-tier color-coded weather warning system, with red representing the most severe, followed by orange, yellow and blue.

Since June, continuous downpours have lashed large parts of southern China and the water levels of many rivers in the affected areas exceeded the danger mark.

China's Ministry of Water Resources has called for all-out efforts to prevent floods and has dispatched teams to affected areas to facilitate flood prevention and control.