Supermarkets need to "up their game" when it comes to the screening of food products before they are stacked on shelves, according to Minister of Agriculture Damien O'Connor.

This follows the Ministry for Primary Industries (MPI) confirming this morning three needles had been found in a punnet of Australian exported strawberries in an Auckland Countdown over the weekend.

O'Connor said in incidences where food products are being sabotaged, the logical thing for supermarkets to do is put in place more checks.

In the past when foreign substances, such as metal filings, have been found in products, some supermarkets have used metal detectors to detect anomalies, he said.

This is one such area supermarkets could explore, he suggested.

"It will be up to the [shops] to work out if they have a production system that's open to possible contamination, and then it's up to them to make sure they shut down that pathway."

He said adapting to food safety issues is a "normal part of evolving food production systems".

Yesterday, O'Connor said Countdown could have done more to prevent the situation, given the warnings he believes it received in light of the situation in Australia.

Today, he said the industry needs "to up their game to make sure there is less possibility of contamination – that goes for any food system."

In terms of the contaminated punnet sold in Auckland over the weekend, O'Connor said he understands that it was shipped from Australia after its Government implemented new export safety requirements.

But he is still not able to definitively say if the sabotaging occurred in New Zealand or across the Tasman.

Acting Prime Minister Winston Peters says as well as the screening of strawberries in Australia, New Zealand has its own security screening here as well.

But he says it is too early to tell if biosecurity screening needs bolstering, as so far only three needles had been found.

Meanwhile, O'Connor is still urging caution when it comes to eating strawberries – "at this stage it's not good to throw a whole strawberry in your mouth," adding the best method is to cut the berries into pieces before consumption.