More than 30 workers have been found crammed into a three-bedroom house, each paying $100 a week, in a shocking abuse of workers in Victoria's labour hire businesses.

In other cases, workers were found to be sleeping on thin mattresses in garages, without access to bathrooms or kitchens, while other employers were caught charging workers to watch television or for the use of work tools and underpaying workers thousands of dollars.

Treasurer Tim Pallas. Credit:AAP

The shocking abuse of workers has been revealed amid the launch of a new licensing regime for the industry.