China's national observatory on Saturday morning renewed a yellow alert for heavy fog in some parts of the country.

On Saturday, thick fog is anticipated to envelop parts of the Bohai, Yellow and the East China Seas, as well as coastal waters off the Liaodong and Shandong Peninsulas, and in Zhejiang and Fujian Provinces, according to the National Meteorological Center.

Visibility in some affected areas will be reduced to less than 1 kilometer, the center said.

Vessels engaged in sailing and operations have been advised to enhance their lookout, adjust speed and maintain a safe distance to ensure safe navigation.

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

(Cover image via CFP)