New Zealand dairy giant Fonterra on Thursday announced a formal and independent review into the circumstances surrounding a global recall of infant formula made from its product.

At a news conference in Auckland on Thursday afternoon, Fonterra Chairman John Wilson described the situation as an " absolute nightmare" and apologized to consumers once again on Fonterra's behalf. "I apologize to mums, dads and caregivers for any confusion and concern," he said.

Wilson said the formal review would be a separate investigation to an operational one currently underway.

"There are serious lessons that need to be learnt from this, and that is why, in addition to the operational investigation our chief executive has already committed to, the Board will be conducting a comprehensive formal review of its own," he said.

The dairy co-operative revealed on Saturday that 38 tonnes of its whey protein used by other manufacturers, including baby formula manufacturer Nutricia, was contaminated with a bacterium that can cause botulism.