The Supreme Court said the controlled use of the less-polluting "green firecrackers" -- developed by federal research institutes to reduce particulate and gas emission -- would be allowed for limited periods between Saturday and Tuesday.

During Diwali, a major Hindu festival of lights, widespread bursting of firecrackers adds to the already high pollution levels in Delhi.

The city, home to some 30 million people, routinely ranks among the world's most polluted capitals, with thick smog shrouding the city each winter.

During the peak pollution period, concentrations of PM2.5 -- tiny airborne particles that penetrate deep into the lungs -- regularly surge to more than 60 times the World Health Organization's recommended daily limit.

A ban on the use of firecrackers during Diwali has been widely ignored in past years.

In an effort to balance cultural celebrations with urgent environmental concerns, the court said only licensed manufacturers can produce certified "green" crackers.

Sales will be limited to designated outlets, with each product bearing a QR code listing its chemical contents.

Online sales remain banned.

Police have been instructed to form patrol teams to ensure compliance and take action against violators, while pollution control agencies have been ordered to monitor and report air quality levels during the festive period.

Environmental activists have in the past expressed strong scepticism about the actual efficacy of less-polluting crackers, arguing that they still pose significant risks to public health and the environment.

On Wednesday, harmful PM 2.5 particles surged to 75 on the air quality index, three times the WHO's daily recommended maximum exposure, according to international monitoring company IQAir.