Bosses who underpay workers would be sent to jail under a plan floated by senior union leader Tony Sheldon.

The call follows a string of scandals at franchise operators 7-Eleven, Caltex, Dominoes Pizza and Pizza Hut, where employees have been underpaid by tens of millions of dollars.

Labelling that as "wage theft", Mr Sheldon told AM it was time to treat bosses with the same rules as employees.

"If you were to steal [money] out of their till, you would go to jail," Mr Sheldon said.

"But they have stolen millions of dollars of payments to their own employees.

"They see it as part of their own corporate strategy on how to minimise payment while maximising their own profit — and that's theft."

Mr Sheldon, who is Secretary of the Transport Workers Union, said there was no easy path to hold a business to account and have a court "properly deal with this criminal activity".

"It's seen in corporate life as just another part of business," he said.

"If you don't get caught, you get away with it.

"If you get caught, well, you pay some people some money if they're game enough to go ask for it."

Mr Sheldon said his call was not political payback for the Government passing the Registered Organisation Act, which imposes harsh penalties on union leaders who breach their duties.

He said the Act was "clearly failing to hold employers to account", and that it was largely aimed at operations of the businesses themselves, rather than the actual act of theft.

"If an employee, or an organisation, takes up an underpayment claim — a wages theft claim — there is no jail term attached, or potential jail term attached to that particular case," he said.

"[The business] should be held to account, just as an employee would be if they were to steal those sums of money."

Mr Sheldon will push Federal Opposition leader Bill Shorten to adopt the position as official Labor Party policy at the party's next national conference.