Greenpeace protesters have shut down work at the site of a proposed dairy farm extension in the Mackenzie Basin early this morning.

Protesters locked themselves onto diggers and other machinery, disrupting construction on an irrigation pipeline for the new dairy farm near Aoraki, Mount Cook.

"Our message is clear," Greenpeace Sustainable Agriculture Campaigner Genevieve Toop said. ​"For the sake of the Mackenzie and our rivers, industrial dairy expansion has to stop."

Greenpeace said the Mackenzie is home to the endangered native kakī/black stilt and claims it is not suitable for dairy farming.

The Mackenzie is a naturally dry region. Greenpeace said its soils are characterised as well-drained, or "leaky", which means agricultural pollution could easily leach into waterways.

The proposed new dairy farm, owned by Dunedin accountant Murray Valentine, has almost all the consents and permissions it needs to go ahead.

The Government is re-writing the regulations around freshwater and agricultural pollution. That's due to be released later this year.

Nearly 30,000 people have signed the new Greenpeace petition to ban new dairy conversions across New Zealand.