The federal government is pushing back against an attempt by big retailers, including Coles and Woolworths, to wind back workers’ penalty rates.

Workplace Relations Minister Murray Watt will make an unusual intervention with a submission to the Fair Work Commission, responding to a proposal that would allow retailers to take away penalty rates, meal breaks and overtime for a 25 per cent pay rise.

“We’re for pay rises, but we don’t think that minimum safety net conditions … should be stripped away for what will end up being a fairly small pay rise for low-paid workers,” he told ABC on Friday.

“If anyone thinks that Woolies and Coles and the other big retailers are doing this to pay their workers more … well, I’ve got a Sydney Harbour Bridge to sell you.”

Watt said that while some workers might prefer the offer, negotiations should happen in a “safer, more supervised context” like enterprise bargaining.

About one million Australian workers are covered by the retail award. Many earn about $54,000 a year.

Other big retailers to support the submission from the Australian Retailers Association include Kmart, 7-Eleven, T2, Barbeques Galore and Mecca.

The Australian Retailers Association, which filed the original submission, claims changes could help simplify General Retail Industry Award.

“But you can simplify award without cutting workers’ pay,” Watt said.

“We need to remember that the workers we’re talking about here are not highly paid people … [They] don’t have enormous bargaining power, and we need to preserve those minimum conditions through our safety net.

“We want to see wages grow in this country, not go backwards, and we’re prepared to step in and try to protect penalty rates and those other conditions.”

The most significant part of the ARA’s proposal would allow senior staff paid up to about $62,000 a year to take a 25 per cent pay boost and opt out of award conditions such as penalty rates, overtime, minimum rates and breaks.

The ARA also wants to void workers’ rights to unpaid meal breaks, to take rest breaks at the end of their shift and to bring in split shifts.

The ARA has accused unions of waging a misinformation campaign around penalty rates.

“There is no proposal to remove penalty rates, overtime or paid breaks from the award,” chief industry affairs officer Fleur Brown told the Australian Financial Review.

“What the ARA has proposed is that managers can opt into a pay increase if they select the voluntary salary absorption option. This will only apply to employees that agree to it.”

The organisation said it had calculated that a full-time senior staffer working two hours overtime a week for a weekly wage of $1176 would be $186 better off under its 25 per cent buyout.

-with AAP