Delhi is the world's most polluted capital and its air becomes particularly bad from mid-December to February as heavy, cold air traps dust, vehicle emissions and smoke from burning crop stubble in states like Punjab and Haryana.

The ban will remain in force until Jan 1.

New Delhi has the worst air quality of all world capitals, but even by its standards Friday's reading was extra bad, as people paid the price for celebrating India's biggest festival in the noisiest, and most smoky way.

The mayor says they cannot afford a huge congregation of people on New Year's Eve.