Winston Peters backs Shane Jones' attack on Fonterra, Jacinda Ardern dismisses it

Days before Jacinda Ardern is due to go on maternity leave, she's facing questions over the stability of the coalition.

On Wednesday, New Zealand First Minister Shane Jones called for the resignation of Fonterra's chairman.

He said the country's biggest company should "focus less on interfering in politics and more on justifying the money they've lost overseas".

On Thursday Winston Peters, about to become the acting Prime Minister, backed him up.

"I think somebody should have been making a comment a long time ago," Mr Peters told Newshub.

However, the Prime Minister says that's not the Government's position.

"He's shared a personal opinion, it's not government policy, and that's the end of the story," Ms Ardern told Newshub.

National MP Paul Goldsmith says her response has been weak.

"She made it quite clear that it was a step too far last time, and he's done it again," he says.

"Instead of saying 'that's your second strike, you're out next time', she says 'oh well it's just a personal opinion'."

National MP Nathan Guy says it's an issue of stability within the coalition.

"She'll say things like 'oh that's just Shane', but really it's an issue for the Prime Minister."

Fonterra chairperson John Wilson refused an interview with Newshub.