A pod of 39 pilot whales have died after becoming beached in a remote area in New Zealand.

The whales were spotted near the GoldenBay on New Zealand's South Island, but rangers were powerless to stop them from being washed ashore, conservation officials said.

Twelve of the whales were found dead on the beach, but the rest were euthanised, as there were slim chances of carrying them back to the ocean.

"We carefully weighed up the likelihood of being able to refloat them and get them safely back out to sea," John Mason, GoldenBay conservation services manager said.

"But our staff, who have extensive experience in dealing with mass whale strandings in Golden Bay, determined that due to various factors it was unlikely they could be rescued," he added.

Whales becoming stranded and beached are common in New Zealand, especially during summers.

Pilot whales belong to the dolphin family and grow up to 20 feet in length and can weigh up to three tons.

Large numbers of whales become stranded on New Zealand's beaches each summer as they pass by on their migration to breeding grounds from Antarctic waters.

Scientists do not know what causes mass beaching of whales.

Over 5,000 whales and dolphins were recorded stranded across the New Zealand coast in the past 160 years