Heavy fog that has shrouded parts of eastern and northeastern China has severely affected highways and flights.

About two-thirds of the area of east China's Shandong Province continued to be masked by the lingering fog on Sunday, reducing visibility to as low as 50 meters.

Two return flights were cancelled and 15 others were delayed at Jinan Airport, local aviation administration sources said.

The fog also forced the closure of many highways in the province, according to traffic authorities.

Many highways of northeast China's Liaoning Province have been closed for more than 12 hours.

The meteorological observatory of Shenyang, the provincial capital, issued six fog warnings from Saturday evening to Sunday morning.

More than 40 flights were affected at the Shenyang-based Taoxian International Airport.

Meteorologists say high humidity in the air and little wind in the past week has caused the fog.

The fog was forecast to disappear by Sunday noon.