Prime Minister Scott Morrison has stepped up his attack on unions, saying with Labor in power there would be more pressure and restrictions on employers and ultimately jobs.

He says a vote for Labor at the May 18 federal election would give unions control over industrial laws and the Greens control over environmental laws.

“I don’t want to see the Labor party get to office where they tie businesses up with all sorts of union red tape and all sorts of the Greens’ green tape, which would just cost people jobs,” he told The Age and Sydney Morning Herald.

“This election is very much about not allowing the Labor Party to basically give militant unions of this country a blank cheque and unhindered interference in the Australian economy.”

Opposition Leader Bill Shorten wants to restore Sunday penalty rates, lift the minimum wage and protect the rights of workers and unions when they are negotiating enterprise bargaining agreements.

Mr Morrison said Labor could not be trusted with the economy as outside forces – such as the tensions between the US and China – threatened growth.

“I think that heightens the risk at a time when uncertainty is great enough in terms of what the world is dishing up to us,” he said.

“So now is the time for responsible and careful budgeting and expenditure.”

Mr Morrison and Mr Shorten will hold their third and final debate in Canberra on Wednesday night.