On the complaint by officials of BEST's vigilance department, the Byculla police have registered a case against the official Mikadar Ratlamwala, a senior police officer said.
The vigilance officers of the civic run BEST undertaking had raided the unit in Byculla and checked its electricity meter, he said.
During the checking it was found that electricity was taken illegally, the police official added.
This practise was being followed since the last seven years and the firm had consumed around 40 lakh units of electricity worth Rs 10 crore, he said.