A traffic policeman directs traffic amid thick fog on a high-way in Yichun, East China's Jiangxi province, Nov 11, 2011.

BEIJING - Thick fog would blanket China's southern regions Saturday morning, the National Meteorological Center said, warning of increasing safety risks on roads and docks, as well as at airports.

The country's top meteorological authority issued a blue alert at 6 am, urging people in fog-affected areas to be aware of the air quality which would be worsened by the fog and to reduce driving speeds to ensure safety.

Fog and haze would decrease visibility to within 1,000 meters in some parts of Shandong, Jiangsu, Anhui, Zhejiang, Fujian, Jiangxi, Hubei, Hunan, Chongqing, Guizhou and Yunnan, and as low as 200 meters in some areas, the center said.