New Delhi decided on Saturday to close its schools for a week due to air pollution, which has reached alarming levels in recent days.

"From Monday, schools will be closed so that children do not have to breathe polluted air," Prime Minister Arvind Kejriwal told reporters.

Government data showed pollution levels in the megacity were 437 on a 500-point scale of the Air Quality Index.

Civil servants will have to work remotely, and private companies have been urged to do so as much as possible.

Construction work will also stop for four days, starting from Sunday, to stop polluting emissions from external sites.

Pollution levels in New Delhi were also at the "extreme" level Friday, which prompted the Central Pollution Control Board to issue an imminent health warning.

The burning of agricultural waste continues in the states bordering New Delhi despite being banned by the Supreme Court.

The Indian capital of 20 million people is the most polluted in the world according to a report by Swiss air quality organization IQAir published in 2020, due to its factories, traffic congestion and agricultural fires lit every winter.