Rescuers have formed human chains in an effort to save hundreds of beached whales which have swam aground at a remote beach in New Zealand.

Several pods of pilot whales totalling more than 650 animals have run aground at the Farewell Spit at the tip of the South Island over two days.

A fresh pod of 240 whales was stranded on Saturday morning.

Hundreds of volunteers rushed to help and have managed to save 100 whales after helping them back out to sea.They formed human chains to prevent the animals from beaching themselves once again.

However around 335 have died and more than 200 are currently stranded and are in a perilous situation unless they can be swiftly returned to the water.

Amanda Harvey from the Department of Conservation Golden Bay had earlier said volunteers from nearby were desperately trying to help refloat the whales.

"We had a group of volunteers camped out overnight and they were ready daybreak to come and help out," she said.

It's not clear why whales strand themselves, though some theories suggest it could be a result of chasing prey too far inshore, trying to protect a sick member of a group, or trying to escape a predator.

Once trapped on dry land, the animals often die from dehydration, as a result of collapsing under their own weight, or drowning when high tide covers their blowholes.

New Zealand has some of the highest rates of whale beaching in the world, and the Farewell Spit beach has also been the site of previous mass strandings.

The largest was in 1918, when about 1,000 pilot whales came ashore on the Chatham Islands.