The Green Party wants the Government to take a tougher line on regulating the use of plastic shopping bags by retailers.
The government in Italy has banned the use of polyethylene bags.
Green MP Keith Locke says Italy is leading the way on the issue and the New Zealand Government needs to do more.
He suggests a government levy on plastic bag use would be a first step, eventually followed by a complete ban.
But the Retail Association believes a total ban is impractical and that voluntary efforts to cut plastic bag use are working.
The Warehouse charges 10 cents for each bag. While usage has dropped by 82%, the chain says there will always be situations where people want to buy a plastic bag.