The accused, identified as - Radeshyam Tiwari, Rajesh Dubey and B R Yadav, forged the rubber stamps and signature of Thane Police Commissioner and pretended that they had obtained the permission for operating the security agency, Vijay Shinde, Inspector, Thane Crime Branch said.
The racket came to light during an inspection of the security establishments carried out by a police team.
The agency provided security services to more than 200 establishments, including banks and builders, in Thane and Mumbai, he said.
Further investigation is on, he said.