A handful of people have chained themselves to a South Canterbury Fonterra factory, to protest against the organisation's burning of coal to power its processing plants.
Members of Coal Action Network Aotearoa (CANA) have blocked off two gateways used to deliver coal to the Clandeboye factory, which is one of the co-operative's largest manufacturing sites.
The group claims Fonterra is the country's second largest coal user, and that Clandeboye alone burns 180,000 tonnes of coal a year.
About 24 people have been taking part in the protest, including former Green Party co-leader and CANA member Jeanette Fitzsimons, who said the company's coal use was contributing to climate change.
She said Fonterra's coal use was growing and this should not be allowed, when climate change was such an urgent issue.
Ms Fitzsimons said the company would not change its fuel use until it was forced to, but she believed the tide would turn and public opinion would eventually force them to.
"If people start associating infant milk formula with burning the dirtiest fuel there is, that's really bad for Fonterra's brand and I don't think they're sufficiently concerned about that."
Ms Fitzsimons said it was a huge irony that farmers were desperately coping with serious drought, some of which was being caused by a changing climate.
"Fonterra's going flat-out changing the climate further, they're not joining the dots."
CANA said today's action was not a one-off protest and that the group had been conducting action against Fonterra for some time. The group said this included meeting with management, but it had not been listening.
The protest started at 7.30am and Ms Fitzsimons said they would be there until the company had got the message.
About two cubic metres of woodchip was dumped in front of the blocked-off entrance by the protesters to demonstrate the alternative energy sources Fonterra could use.
Fonterra said it understood and shared CANA's position on coal, and believes a transition away from the fossil fuel will be the only sustainable future for dairy production.
Fonterra said it had had ongoing dialogue with the network over recent years and it was conscious of the impacts that all industries had on emissions.
It said it was committed to reducing environmental impacts across its operations.