A grouping of health providers, consumers, academics and unions - the ACC Futures Coalition - says the Government should not privatise insurance in the workplace because there are benefits in having a purely state-run system.
The coalition commissioned a report on proposed changes, which include extending the Accredited Employer Programme and opening up workplace insurance to private insurers.
Spokesperson Hazel Armstrong says there are benefits in having a fully state-run system.
She says ACC can negotiate deals with other government departments and co-ordinate services such as rehabilitation.
ACC Minister Nick Smith says if any changes were to happen, the government would make sure employees get the same care if their employer decides to move to private insurance.
He says opening it up to the private sector will benefit ACC, because it will be competing for the best cover available.