Parents in New Zealand are being told to stop feeding their infants Nutricia Karicare follow-on formula amid concerns it may contain a bacteria that could cause botulism.

New Zealand Ministry of Primary Industries (MPI) on Saturday identified Nutricia Karicare follow-on formula as a product made in New Zealand potentially containing contaminated whey protein from Fonterra's Hautapu manufacturing facility.

New Zealand dairy products giant Fonterra warned that bacteria had been found in three batches of a particular type of whey protein concentrate.

The scare covers some 40 metric tonnes of contaminated whey protein, which is used as an ingredient in a further 900 tonnes of product.

The batches of Nutricia Karicare follow-on formula, potentially contaminated with the life-threatening bacteria botulism, are not thought to be on New Zealand shelves.

But the acting director general of the MPI, Scott Gallacher, said that he was advising parents not to use the formula as a precaution.

Gallacher named the countries involved as Australia, China, Malaysia, Thailand, Saudi Arabia and Vietnam.

New Zealand Trade Minister Tim Groser said that agencies acted to immediately inform authorities around the world as soon as they became aware of the risk.

"New Zealand authorities are working with Fonterra to identify and trace all potentially affected products and then inform regulators around the world," he said.

New Zealand Food Safety Minister Kikki Kaye urged consumers to follow MPI's advice.

"My primary concern is that people are safe and that the public have the information they need to keep them safe," Kaye said in a statement.

"I advise parents and caregivers to take a precautionary approach and seek health advice if they have any concerns."

Fonterra said eight of its customers were potentially affected by the contamination but refused to identify them.

Gallacher said Nutricia has manufactured five batches using the contaminated whey protein, although there are claims none of them have been sold.

Nutricia had told MPI that all of the batches were either in a warehouse, being shipped, or in storage in Australia, however Gallacher said he was still advising parents using the formula to change products.

"MPI is still in the process of verifying this information, and today sent a team to Nutricia's Auckland warehouses," Gallacher said.

Parents should instead use Karicare infant formula for children aged 0-6 months, ready-made formulas, or alternative brands.

Gallacher said he understood the contamination affected about 40 metric tonnes of product. This had found its way as an ingredient into around 900 tonnes of further product.

"It ranges across a wide range of products, from infant formula, through to yoghurt and beverages and protein drinks. Clearly we are trying to get to the bottom of exactly the full range of those products so that we can ensure that consumers and overseas markets get the right sort of information at the right time."

So far, Nutricia Karicare was the only product MPI was aware of which could be affected in New Zealand, but he stressed that this was on the basis of rapidly changing information.

Botulism is a rare but serious illness caused by a bacterium which occurs in soil. It produces a toxin that affects nerves. Foodborne botulism comes from eating food contaminated with the toxin. Intoxication botulism can result when food processing failure and/or temperature abuse allows germination of spores and proliferation of vegetative cells.