Hundreds of whale carcasses popped 'like balloons' to stop them exploding on New Zealand beach

Around 400 die after one of the biggest strandings in country's history

A member of the public looks at the dead Pilot whales during a mass stranding at Farewell Spit on February 11, 2017. (GETTY)

Conservation workers in New Zealand have been “popping” pilot whales “like balloons” to stop their carcasses exploding.

Around 400 whales died after one of the largest ever strandings in the country’s history.

The public has been warned about the dangers posed by “whales exploding” on Golden Beach, on the South Island, and the Department of Conservation (DOC) has cordoned off the area.

Workers spent Monday cutting holes in the animals, using knives and two metre needles, to release internal gases. It was “like popping balloons,” a DOC spokesperson told local radio.

It would take several months for the bodies to decompose and turn into skeletons.

The surviving whales were last seen swimming six kilometres (four miles) offshore on Sunday evening, according to DOC.

Last Thursday, a pod of about 400 whales became stranded, with a second pod of more than 200 whales stranded on Saturday.

The precise cause is not known.

Beached whales are not uncommon on Golden Bay. Its shallow muddy waters confuse the whale's sonar, leaving it vulnerable to stranding by an ebb tide, according to marine environmental organisation Project Jonah.

Pilot whales are not listed as endangered, but little is known about their population in New Zealand waters.