The Ministry for the Environment has developed an online complaints portal for consumers to report retailers breaking the law by supplying single-use plastic bags.
From today, retailers are prohibited from supplying single-use plastic bags. The ban applies to all plastic bags with handles, including thicker boutique-style plastic bags and any that describe being "biodegradable". It does not include roll plastic produce bags commonly found in supermarkets and greengrocers.
Retailers who continue to supply the plastic bags face prosecution and subsequently a fine of up to $100,000 under the Waste Minimisation Act. However, the Ministry for the Environment says the organisation is taking a more measured approach and there will be warnings before a financial penalty.
Random mystery shopper-style audits will also be carried out to catch retailers who continue to supply single-use bags.
Retail NZ general manager of public affairs Greg Harford said he did not expect retailers to continue to supply plastic bags from today, though if they did it would likely be smaller independent operators who thought the ban only applied to large chains.
"There's been a little bit of confusion about the scope of the ban because some businesses have tried to do the right thing by moving to compostable biodegradable bags, but those are also included within the scope of the ban," Harford said.
"There's still a bit of education to do but most businesses are on track to stop issuing bags."
Harford said retailers had been trying to use up the remainder of their stock of plastic bags in the past six months since the ban was announced.
Blanket ban: No more single-use plastic bags after July
Plastic produce bags were exempt from the ban because of food safety reasons around contamination, he said.
"Customers are increasingly concerned about plastic and they're going to be pushing back pretty hard on anyone who is actively flouting the ban. Customer pressure will make sure retailers are following the law well ahead of any regulatory action."
The ministry will police the ban on a warning based system before penalties are imposed. It will also conduct random audits of retailers and has set up a portal that will allow consumers to report any retailers who continue to supply the bags.
"We will contact businesses we confirm as not complying, and we will work with them to figure out why they haven't stopped giving out single-use plastic bags," a spokesman for the ministry said.
"The Government does not have prosecution targets or a goal to prosecute retailers. Our priority is to obtain compliance, and that's why businesses were given six months to phase-out the bags."
The spokesman said a financial penalty would be imposed by the court if a business continued to fail to comply, though the ministry said it hoped to not to have to go down that route.
"Prosecutions are costly and time consuming for both parties, which is why our priority will be ensuring retailers understand the ban and the alternatives available, so they can do what's right for our environment."
The Government announced single-use plastic bags would be banned in December last year and signalled the move in August.
Retailers have been supportive of Government's plans to ban plastic.
Supermarket giants Woolworths NZ and Foodstuffs which operate Countdown, New World, Pak'nSave, Four Square, and Gilmours stores led the way with the single-use plastic bag phase out, with self-imposed deadlines to no longer offer plastic bags from the start of the year.
Woolworths NZ and Foodstuffs have also signed the New Zealand Plastic Packaging Declaration along with 10 other companies to commit to move to 100 per cent re-usable or compostable packaging by 2025.
Countdown said it had removed 1889 tonnes of plastic from circulation in New Zealand since May last year - the equivalent to eight fully loaded jumbo jets.
Kiri Hannifin, general manager of corporate affairs, safety and sustainability at Countdown, said the retailer's plastic reduction strategy had diverted 278 million single-use plastic shopping bags from landfill.
She said 90 per cent of Countdown customers now brought their own bags or used no bag when they shopped. This number had increased month-on-month since Countdown began phasing out single-use plastic carrier bags in May last year.
Harford said retailers were now beginning to look at how they could reduce plastic packaging from their stores. But he said New Zealand lacked the infrastructure to be able to recycle soft plastics which made it a challenge.
Soft plastics recycling was halted last year due to a massive backlog but the scheme has restarted in Auckland to avoid stockpiles of bags being sent to landfill.
Councils in Canterbury are also now running a soft plastics collection scheme.