The Special Task Force of Bengal police late on Wednesday recovered 81,000 detonators from an SUV in Birbhum’s Mohammedbazar.

Sources said this haul was the largest in recent memory.

The supply of explosives was from Bihar’s West Champaran district, said a senior STF officer in Calcutta.

SUV driver Asish Keura of West Burdwan has been arrested. “We are trying to find out the name of the sender and end user. We will visit Champaran to find out the warehouse,” said the STF officer.

Detonators are usually used in stone and coal mines to create blast force. Illegal mines usually use smuggled detonators. A Maoist angle can’t be ruled out, sources said.

Birbhum has a large belt of stone mines and crushing units. All legal establishments get their explosives through a special permission from the mining department. Smuggled explosives are usually used by owners of illegal stone mines.

“The quantity of smuggled detonators is huge and we have doubts as to whether those are only used in illegal mining. We can't rule out involvement of Maoists….," said an official.

According to a senior official in Birbhum, if all those explosives were meant for illegal stone mines, then it proved "rampant" illegal mining.

In February last year, Birbhum police had seized an SUV and recovered 25,000 detonators from the vehicle.