China's national observatory Sunday continued to issue a yellow alert for thick fog that will shroud parts of the country in the morning.

Thick fog is forecast to affect parts of Liaoning, Beijing, Tianjin, Hebei, Shandong and Jiangsu, reducing the visibility to less than 200 meters in some regions, according to the National Meteorological Center.

It suggests drivers in affected regions slow down, while airports, expressways and ports take appropriate safety measures.

China has a three-tier color-coded warning system for fog, with red being the most serious, followed by orange and yellow.