Nearly 8,000 passengers were stranded due to airport closure when thick fog blanketed this capital of southwest China's Sichuan Province on Sunday morning.

The heavy fog cut visibility at the Chengdu's Shuangliu International Airport to less than 20 meters, delaying flights and requiring others to be rerouted.

China Civil Aviation Administration's regulations say that an airport's standard visibility for taking off and landing is 550 meters and 800 meters respectively.

Lu Junming, an official in charge of passenger service at the airport, said the fog forced the airport to close for two and half hours from 7:10 to 9:40 a.m. Sunday.

A total of 97 flights were delayed while six others were cancelled, affecting thousands of passengers, Liu said.

The airport offered drinking water to stranded passengers waiting for departures.

The fog got thicker on Saturday night due to high humidity and a temperature drop, according to the city's observatory.

The visibility in the downtown area is less than 200 meters. The observatory predicted that the fog would hit the city again on Monday morning.

The heavy fog also caused the closure of all major highways linking Chengdu with other cities in the province.

No serious traffic jams were reported during the morning rush hour, and many people turned to public transport instead of driving their own cars for safety reasons.