The three firms have written to businesses asking for up to £250 for health and safety information, inciting hundreds of complaints to the HSE.
The three groups, Liverpool-based Health and Safety Enforcement Agency (HSEA), Manchester-based Health and Safety Compliance Agency (HSCA) and Rochdale-based Registration Enforcement Division (HSRED) all request cash in exchange for health and safety registration.
Justin McCracken, deputy director-general at the HSE, said: 'None of these companies is connected to HSE.
Organisations should be very wary of any approach from these firms, or any company offering similar services. All three firms use wording suggesting they are official enforcement bodies but they are not.'
The HSE has said that fleets receiving such information should ignore it, as there is no legal need for anyone to buy literature or services from these companies.
The Government body is currently liaising with trading standard offices and the police, who are investigating all three companies.
Fleets can purchase a Health and Safety Starter Pack: Health and Safety Advice and Guidance for New and Small Businesses from the HSE for £30. Visit www.hsebooks.com