Unions will push for a radical overhaul of Australia's workplace relations laws that would allow millions more workers to push for substantial wage increases.

ACTU secretary Sally McManus, in an interview with Fairfax Media, described the current system of negotiating wages as a "joke" and outlined proposals unions were working towards.

The push will put pressure on Labor ahead of the next election to make significant policy changes to the Fair Work laws the party introduced less than a decade ago.

"We think that workers should be able to organise where the power is," Ms McManus said.

That is expected to involve unions being able to negotiate across entire industries or supply chains to set pay and conditions - a significant break with the orthodoxy of the past 25 years.

Ms McManus also wants major changes to how the pay of millions of low-paid workers are set in awards, the wages safety net.

"The awards have been either left to wither or been stripped back," she said. "Unions can't move the award forward anymore."

Pay increases in awards should not be tied to increases in the minimum wage, she said. Instead workers should be able to push for much higher pay rates.

Ms McManus comments come amid concern over weak wages growth and a series of scandals over wage theft and underpayment.

"You've now got a situation where the minimum wage is not enough to pull you out of poverty and underneath that you've got that one in 10 workers are on temporary work visas," she said.

"And then you've got wage theft dragging things down, 40 per cent of people are in some form of insecure work."

Ms McManus said unions are still working on the proposals, the full detail of which will likely be announced early next year. "We want to make sure solutions we propose are rigorous, are flexible and are going to last for at least a couple of decades."

Any changes to allow a type of industry wide bargaining would be controversial and be met with resistance from employers.

Ms McManus cited the community sector where unions are forced to negotiate with small organisations which are typically funded by governments. Unions, she said, should be able to bargain directly with governments to set wages and conditions across that sector.

Elsewhere unions could bargain with head contractors or franchisors, which would then allow pay and conditions to be set across entire industries or supply chains.

"Employers might organise themselves in a certain way, you should be able to bargain where that power is," Ms McManus said.

This would mark a significant break with the past 25 years when the Keating government first introduced enterprise bargaining as a way to tailor wages and conditions to an individual firm.

Under the Fair Work Act there has been a shift in recent years away from enterprise bargaining - which typically pays much higher wages and conditions - to the award.

Nearly a quarter of all workers are now on the basic wage rates of the award compared to just over 15 per cent in 2010."There's a huge gap between (wages from) bargained outcomes and the award," Ms McManus said.

"Unions have been bargaining and the system we've been working in has created huge incentives to cancel agreements, to use labour hire and contract out work."

It has become common for employers to cancel agreements and move workers onto the award.

That can often cut workers' pay significantly. "Enterprise bargaining is a joke because employers can threaten you with a 30 per cent pay cut," Ms McManus said.

Ms McManus said the Fair Work laws were introduced around the time of the global financial crisis and the economy has since been reorganised.

That includes greater use of contracting out, franchising and now the gig economy. Wage rises were now no longer linked to increases in productivity, she said.

The only tool unions had to raise wages was enterprise bargaining which was "so restrictive it's not funny."

"It's over-regulated with so much red tape, who you can bargain with, what you can bargain for, ways you can exercise power."

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