India's top court has stopped firecracker sales in and around New Delhi as the worst season for air pollution begins.

The Supreme Court on Friday asked the government-run Central Pollution Control Board to study and report in six months on the harm caused by the materials in firecrackers.

The court ordered the federal government not to renew licenses of firecracker sellers until further orders.

New Delhi's air pollution is among the world's worst and peaks in because of weak winds and the countless fires people set to stay warm.

The fireworks set off during the Hindu festival of Diwali in September caused measurements of tiny lung-clogging particulate matter to reach dangerous levels above 300 micrograms per cubic meter.