Supermarkets tighten security

Parents looking to buy infant formula will now find the food behind service counters or be limited to two cans in some supermarkets following a 1080 poison threat.

Countdown and Foodstuffs have heightened security at its stores after police yesterday revealed they had spent more than three months investigating a blackmail threat to poison infant and other milk formulas.

Countdown's acting managing director Steve Donohue said there was additional security in place, from the time the product arrives in its distribution centres to when it's bought by customers.

"Some of these security measures will mean it takes a little bit more time for customers to purchase infant formula, but together these steps will ensure constant monitoring of the product, either in person or by CCTV," he said.

Mr Donohue said there will be extra checks in-store before the product is placed on the shelf, and infant formula will be moved to behind service counters or Lotto desks.

Random sampling will also be carried out.

"We're also asking our customers to be vigilant," Mr Donohue said.

"Everyone has a role to play in checking their cans of infant formula for any sign of tampering, and by keeping an eye out for anything suspicious or unusual."

Foodstuffs has also introduced more security to make sure formula couldn't be tampered with.

"This means all customers entering a Foodstuffs store will be subject to heightened surveillance and there will be higher security in-store," Foodstuffs' managing director Steve Anderson said.

"We know that families will want to ensure they have an ongoing safe supply for their children, and we are committed to managing infant formula supply to ensure product is available for all. To facilitate this, for now, we are limiting customer purchases to two tins per customer per product line."

Mr Anderson said customers will also be given a Ministry for Primary Industries consumer guide, which has details about how to tell whether the product had been tampered with.