WorkSafe Victoria is investigating private security firms subcontracted to guard guests in Victoria’s bungled hotel quarantine program.

WorkSafe chief executive Colin Radford says the health and safety practices of the companies are being probed, but has refused to give up the names of the companies being investigated. He said only that the companies were used across eight worksites.

“We are investigating some of the activities as they pertain to the [Occupational] Health and Safety Act, and the duty holder in that case would be the security companies,” he told Victorian Parliament's Public Accounts and Estimates Committee (PAEC).

“So, absolutely we are investigating whether they have complied with their responsibilities.”