Deputy Prime Minister Winston Peters doubled down on last week's New Zealand First party attacks on the performance and leadership of Fonterra, saying the country's largest business was costing the economy more than $2 billion from food safety and animal welfare scares.

Speaking at the weekly post-Cabinet press conference in the absence of Prime Minister Jacinda Ardern, Peters said in reference to Fonterra: "I think we will not become a great, first world trading nation in the top of the world's trading nations until we face some blunt, commercial facts" and that "I do believe in commercial accountability".

Regional Economic Development Minister, Shane Jones, who is a NZ First party minister like Peters, last week called for Fonterra's chairman to "take the first cab out of town" and resign over the cooperative's commercial performance in comments that Ardern characterised as 'private' rather than made in a ministerial capacity.

Peters stuck to that line but backed Jones, saying: "We made our comments on Fonterra a long, long time before the last election."


Apparently referring to food safety scares earlier this decade, Peters said the cost of Fonterra decisions to the economy had been $1.383b, "including $100m of taxpayers' money trying to sort things out on the wharves and docksides of China".

A further $800m cost loomed, he said, apparently referring to the estimated cost of the programme to eradicate the mycoplasma bovis bacteria from the national beef and dairy herd.

A review of special rules relating to Fonterra's operations, governed by the Dairy Industry Restructuring Act, is currently occurring and Peters left open the suggestion the review could yet lead to a break-up of the cooperative, which was formed in 2001 in an effort to give the New Zealand dairy industry global competitive scale.

"It is possible in a thorough review that conclusions emerge which weren't apparent at the time when you set the terms of reference," he said, while noting that Fonterra itself wanted reforms.

"They, for example, don't want to be required to supply all and sundry, including their export competitors."

Fonterra has been approached for comment.