Fonterra identified the bacteria Clostridium Botulinum, which can cause botulism, a potentially deadly food poisoning, The Wall Street Journal reported Saturday.
The company said the bacteria could be present in three production batches of whey protein concentrate, used in a variety of products, including baby formula. The problem does not involve fresh dairy products, such as cheese, butter and milk, the company said.
The company said it had not received any reports of illness caused by the bacteria, which the U.S. Food and Drug Administration said can be deadly in even trace amounts.
"It is in a range of different products and they have different amounts of sensitivity. The one that honestly we are concerned about is infant formula that's been made from this product," Gary Romano, Fonterra's managing director for New Zealand milk products, said.
The Ministry of Primary Industries said the problem affected New Zealand, China, Australia, Thailand, Malaysia, Vietnam and Saudi Arabia. The problem originated in an unsterilized pipe that was the source of contamination for 38 metric tons of whey protein, Fonterra said.
Fonterra Chief Executive Officer Theo Spierings is headed to China, in part to deal with the tainted products issue, company Director of Communications Kerry Underhill said.
The bacteria was found in whey protein produced in May 2012, but the problem was not noticed until March and the specific bactgeria was not isolated and identified until Wednesday, the Journal said.
Fonterra is the world's fourth-largest dairy company, the New York Times said Saturday.