Almost all firecrackers are manufactured illegally in Bengal since the state has only three licensed units.

According to the Explosives Rules, 2008, all units manufacturing more than 15kg of firecrackers in one lot require a mandatory licence from the Petroleum and Explosives Safety Organisation under the central government.

The law specifies that district magistrates can give licences to manufacturing units producing less than 15kg of firecrackers in one lot, but the units need to share copies of the licence with the safety organisation, formerly known as the department of explosives.

The city office of the organisation, which oversees the issuance of licence in 13 eastern states, has not received any such copy.

The rules also say every manufacturing unit (irrespective of the amount it produces) with a licence has to have a foreman certified by the organisation to oversee the technical aspect of production.

Currently, the state has three such certified foremen to monitor as many licensed manufacturing units, an official said. There is one valid unit each in North 24-Parganas, Hooghly and Burdwan.

South 24-Parganas and Howrah - the hotbed of high decibel firecrackers - do not have a single legal unit.

After getting permission from the safety organisation or a district magistrate, manufacturing units need clearances from the state pollution control board and the fire department.

The firecracker lobby claimed that over 31 lakh people in the state are directly or indirectly involved in the business. A large chunk of them are manufacturers. The lobby has been demanding that the state government raise the permissible limit of noise produced by a firecracker to 125 decibel from 90.

The apex court recently paved the way for relaxing the firecracker noise ceiling in Bengal from 90 decibel at 5m from the point of origin to 125 decibel at 4m from the source. The 90-decibel norm has been in force in the state since 1997.

State pollution control board chairman Kalyan Rudra said: "We have just received the Supreme Court order and are seeking legal advice."

A safety agency official said cops were mandated to monitor and submit a report every six months. "But we hardly get anything," he said.

The green lobby demanded immediate government action against illegal units.