New Zealand is the only country to vote against further protection for the critically endangered Maui's dolphins at the world's largest conservation summit.

A motion, aimed at stopping the extinction of the world's rarest dolphins and porpoises, including New Zealand's Hector's and Maui's dolphins, was put forward at the IUCN's World Conservation Congress in Korea last week.

Some 576 members, including governments and NGOs, voted for the motion. New Zealand is the only country to vote against.

"The New Zealand government has acted shamefully and can no longer claim to be leaders in conservation," WWF's marine programme manager Rebecca Bird said.

"If we fail to act now, it will not be long before Maui's [dolphins] disappear from our waters forever."

The motion included an urgent extension of protection measures, with an emphasis on banning gill net and trawl net use from the shoreline to the 100 metre depth contour in all areas where Hector's and Maui's dolphins are found.

"New Zealand is committed to the protection of Maui's and Hector's dolphin, but is unable to support the proposed motion because it is not consistent with New Zealand government policy on mitigating fishing-related risks to them," 

"It isn't hard to give this species a shot at survival: we need to stop needlessly killing them in fishing nets."

"The Maui's dolphin is the most endangered dolphin species in the world, but we won't stand up for its survival?  It's appalling,"