The Green Party wants the government to back its crackdown on the supermarket duopoly by supporting its member’s bill before Parliament rises for the election.

The Commerce (Excessive Pricing in Retail Grocery Industry) Amendment Bill seeks to ban supermarkets from charging prices that are “excessive” relative to the cost of supplying products, plus a “fair margin”.

Green Party co-leader Chlöe Swarbrick said New Zealanders pay too much for their groceries, while supermarket profits exceed a million dollars a day.

“While Luxon’s government has talked tough, prices at the check-out have continued to rise.

“Parliament can now actually do something meaningful in its final few weeks before the election by supporting this common-sense Bill, to reduce New Zealanders’ bills. At the end of the day, surely, that’s why we’re all there in the first place,” she said.

The Bill is part of the Green’s affordable kai election policy, set to be announced next month, and will be placed in the members’ ballot by the party’s consumer affairs spokesperson Ricardo Menéndez March.

He said it would be up to the courts to decide whether a supermarket had breached the ban — on application from the Commerce Commission — and supermarkets would be required to keep records of their pricing and provide them to the commission on request.

“Breaches would carry penalties of up to $10 million, three times the value of the commercial gain, or 10% of turnover.”

“This is consistent with Australia’s approach, which brought in the same ban on 1 July this year with the same penalties we are proposing here, following its own reviews into supermarket market dominance,” Menéndez March said.

Swarbrick called on the prime minister and the wider coalition to use Parliament’s remaining time to “do something practical” to lower the cost of living.

The government has to attract an international competitor into the market but has been unsuccessful.

New Zealand First has also promised to break up the supermarket duopoly if elected.