Heavy fog Saturday caused the cancellation of four flights and the delay of 63 at an airport in Chengdu, capital city of southwest China's Sichuan Province, stranding more than 5,000 passengers.

Chengdu Shuangliu International Airport (CSIA) was forced to close for three hours as heavy fog shrouded the area from 5:40 a.m.to 9:00 a.m. and reduced visibility to 200 meters, said CSIA official Lu Junming.

The affected flights were domestic. International fights were not affected.

It was the severest flight delay caused by fog at an airport in Sichuan since September.