This picture taken by a passenger inside an airplane at the Beijing International Airport shows haze outside. [Photo/Weibo]

More than 200 flights were cancelled at the Beijing International Airport Friday morning as a thick cloud of smog shrouded the capital.

Out of the 554 planned flights, 200 were already cancelled due to bad weather by 11 am, the airport announced on its Twitter-like Weibo account.

The weather condition is set to get better in the afternoon, it said, suggesting passengers to be prepared for flight delays.

Beijing has issued red alert twice for severe air pollution over the past few weeks and the capital city is expected to remain blanketed by haze for a few more days.

The Beijing municipality's heavy pollution emergency response headquarters issued a blue alert for heavy pollution on Thursday afternoon, saying smog will hit central Beijing and southern suburbs on Thursday night.

It called on residents in these areas to take protective measures.

A cold front will disperse the smog on Saturday, it added.

Roughly 50 cities in northern and eastern China have issued air pollution alerts in the most recent bout of smog.

China has a four-tier warning system, with red as the most severe, followed by orange, yellow and blue.