Major employment groups have joined forces to target the federal government’s plans to close a labour hire “loophole”.

The peak bodies for mining, petroleum, construction, farming, and small and large business – including the Australian Chamber of Commerce and Industry, the National Farmers Federation, the Minerals Council and the Business Council of Australia – have united to begin a national campaign against the proposed “same job, same pay” workplace reforms.

The federal government says the laws would lose loopholes that allow companies that have negotiated a pay rate with their workers to then pay labour hire contractors less for the same job.

But the industry groups argue it would instead deny contract workers the ability to negotiate “more pay for harder work”.

Minerals Council chief executive Tania Constable said the proposed changes would be regressive and affect a large number of industries.

“It affects all of business, it affects service contractors, it affects labour hire, it affects individual organisations – there is no one across Australia that is untouched by this poor policy,” she said on Monday.

“This policy of same jobs, same pay would undermine that productivity that we’re seeing, we will see job losses, it’s unfair.”

Ms Constable said the changes would not reward experience or those who had been with an organisation for a long period of time.

“How is it fair that someone with six months’ experience can demand the same pay as someone with six years’ experience?” she said.

“Our workplaces should be about fairness, reward for effort, and experience. Not a blanket approach that fails to understand that all workplaces are unique and worker ambition and values [are] varied.”

Chamber of Commerce chief executive Andrew McKellar said labour hiring businesses would be limited in their capacity to operate.

“This is all about an agenda to try to restrict those legitimate businesses from conducting their operations, and to deliver outcomes which are basically at the request of unions to try and make it easier for them to recruit members,” he said.

“We will stick to our guns, but I think we’re seeking to raise awareness on these issues.”

But Treasurer Jim Chalmers rejected suggestions the laws would affect productivity.

“What we’re talking about here is making sure that labour hire or casual work or gig work is used the right way and not the wrong way,” he told ABC Radio on Monday.

“It’s not unusual or uncommon for employer peak groups to express a view about industrial relations.

“There’ll be areas where we’ve got similar views and there’ll be some areas where we don’t – we’re realistic about that.”

Dr Chalmers said business groups and unions were being consulted.

He denied the changes would stop businesses from rewarding experience in the workplace.

“It’s about making sure that workers are eligible for the pay and conditions that the employers have agreed with their workforces,” he said.

“We don’t want to see it used as a sort of an ongoing way to undermine and undercut people’s pay and conditions that have been negotiated with employers.”

Mining and energy union general secretary Grahame Kelly said the claims made by the business groups were bizarre and disingenuous.

“It is a very common scenario to see two workers with the same experience doing the same job side by side, but one is paid less purely because they are labour hire and not a direct employee,” he said.

The legislation is yet to be introduced to parliament. In a consultation paper, however, the Albanese government said that overtime or incentives covered in an employee’s enterprise agreement would be payable to a labour hire worker only if they met those same conditions.

The consultation paper does not directly address business concerns about paying for age or experience.

The workplace reforms are due to come into force by the end of the year.

-with AAP