A pod of 28 pilot whales that were left stranded on a New Zealand beach on Thursday are likely be put down as there is little chance of refloating them, wildlife officials said.

Twelve of the whales that beached themselves at Golden Bay on the South Island had already died and the rest were in poor condition, the Department of Conservation (DOC) said.

DOC regional manager John Mason said the whales beached during the highest tide of the month, significantly reducing the chances of getting them back in the water.

"Normally they strand mid-tide but these are high and dry right at the top of the beach," he told AFP.

"The next tide won't reach them and we're mulling our options at the moment, most likely euthanasia."

Mass standings are common in New Zealand and a pod of about 100 pilot whales beached themselves in the same bay last January, with most failing to survive.

Pilot whales are members of the dolphin family and grow up to six metres (20 feet) long.

The reason why they beach themselves in unknown, although scientists speculate it may occur when their sonar becomes scrambled in shallow water.