Nearly 4,000 airport passengers have been stranded for eight hours as dense fog hit an airport in Urumqi, capital of northwest China's Xinjiang Uygur autonomous region on Sunday.

Thick fog started to envelope Urumqi International Airport around 10:30 a.m., reducing visibility to 200 meters, said the airport's operators.

Thirty-eight flights taking off from the airport have been postponed or canceled, and 12 others that headed for Urumqi were forced to land in other airports.

The mist dispersed at about 6:40 p.m., and the operation of the airport is returning to normal.