The federal government has defended the extra billions of dollars employers will be paying workers under workplace reforms, saying it is a fraction of Australia’s total wage bill.

Asked if the reported $9 billion over 10 years in extra wages was an accurate figure, Workplace Relations Minister Tony Burke did not deny the sum, but said it was an “extraordinary amount” for people to be underpaid.

Mr Burke said it was a tiny percentage of the total wage paid by Australian employers, challenging the notion that it would translate into a massive surge in consumer prices.

“That figure, when you look at it as a percentage of Australia’s wages, is one-tenth of 1 per cent of what wages are in Australia,” he said in Canberra.

The changes to workplace laws, introduced to parliament on Monday, are aimed at closing loopholes, including the use of labour hire workers to undercut the rate of pay agreed for employees.

The reforms also seek to criminalise wage theft, bolster protections for gig workers, and create a pathway for casuals to become permanent.

The proposed changes have unleashed a wave of criticism from the Coalition and employer groups, with concerns the legislation will push up the cost of deliveries and other services for consumers, weigh on productivity growth, and trigger job losses.

Opposition workplace relations spokeswoman Michaelia Cash said the coalition wanted to see higher wages for Australians.

“But that cannot be at the expense of businesses, it cannot be at the expense of passing on higher costs to consumers,” she said in Canberra.

Senator Cash called on Mr Burke to allow public hearings for feedback on the proposed changes, saying the government did not need to “ram” the legislation through.

“Let’s work through the complexity, let’s work through the cost, let’s work through the confusion,” she said.

Business groups, which have campaigned against the changes for months, are wary of the scope of the reforms.

Master Builders Australia challenged the notion the changes would have a minimal impact.

“There is nothing simple about adding hundreds of pages to the Fair Work Act and expecting businesses of all sizes and independent contractors to try and navigate it,” chief executive  Denita Wawn said.

Greens leader Adam Bandt said his party wanted more money going into workers’ pockets, but is yet to say whether it will support the legislation.

With the opposition expected to oppose the bill, the government will need support from the Greens and crossbenchers to pass the laws.

The Greens party room will meet on Tuesday morning.

“We’ve been pushing for some years now to ensure that there’s a hard floor underneath Australian labour laws so that people can’t be exploited and paid less than the minimum wage,” Mr Bandt told ABC Radio.

– AAP