New Zealand was one of only two countries to oppose further protection measures for Maui's and Hector's dolphins at the world's largest conservation conference, it has been revealed.

These type of dolphins live only in New Zealand's coastal waters.

The secret vote took place last week at the International Union for Conservation of Nature's conference in Korea, where government officials and environmental groups met to outline environmental policy goals for the next four years.

Some 117 countries and 460 organisations voted for New Zealand to ban gill and trawl nets in waters up to 100 metres deep.

But New Zealand voted against the move, and in a statement told member countries the recommendation is not backed by scientific evidence.

In June, the ministry extended the recreational and commercial set net ban around Taranaki out to two nautical miles offshore.

Environmental groups say the Government can no longer call itself a leader in conservation, following its vote against further measures to protect the dolphins.

The results of the vote are not binding, but Greenpeace's spokesperson Karli Thomas says the New Zealand Government's next move is important and it has to be careful not to further damage its reputation for conservation.

Rebecca Bird, the World Wide Fund for Nature's marine spokesperson, says the Department of Conservation and the Ministry for Primary Industries need to sort out their differences immediately.

"I think it's incredibly sad that the New Zealand Government perspective that's presented at a meeting like this where there is such an opportunity for New Zealand to be the conservation leader they've been known to be in the past.

"It's a lost opportunity and a real shame, and I really do feel for the people present having to carry the New Zealand Government's line on this."