Victoria’s public sector union is using a new inquiry to argue for the rights of casual government workers.

The State Government’s inquiry into the labour hire industry, insecure work and the treatment of short-term workers has begun.

Unions from across industries say exploitation and abuse of casual contracts by employers is hurting workers.

The Community and Public Sector Union says casual contracts and other intermittent work arrangements destabilise workers and their families, who can never know if they will get a regular pay cheque.

The CFMEU says casualisation in the construction workforces leaves employees vulnerable to unethical practices.

In addition, unions for hospitality, manufacturing and health services say casual workers are less likely to speak out about mistreatment.

The inquiry's findings are due on July 31.