The incident took place on Sunday night when four coal pilferers were extracting coal from the mine.
Three men have been trapped while extracting coal from an illegal coal mine at Kulti in West Bengal, an official said on Monday.
An Eastern Coalfields Limited (ECL) rescue team could not enter the mine in Paschim Bardhaman district due to poisonous gas at the mouth of the pit, the ECL official said.
The incident took place on Sunday night when four coal pilferers were extracting coal from the mine, locals said.
"Police informed us that three persons are trapped in an illegal mine at Aldhi village in Kulti. Our rescue team failed to enter the pit twice due to poisonous gas at the mouth of the pit, which is narrow," the official told PTI.
While three illegal miners got trapped inside the mine, the fourth managed to escape, the police said.