A mass stranding of 198 pilot whales in New Zealand has left 24 dead, officials said today.

The whales became stuck on Farewell Spit, a narrow sandbar at the northern tip of the South Island, the Department of Conservation said.

Department staff and volunteers from whale conservation group Project Jonah, planned to try and refloat the surviving whales on the evening high tide just after 5pm local time, spokesperson Jose Watson said.

If the attempt is unsuccessful, the department will ask members of the public to bring buckets, spades and old sheets tomorrow morning to help care for the whales.

Watson said the department had reached out to Project Jonah as their volunteers were trained in dealing with the large mammals, some of which were up to 6 metres long.

“You want people who are fully briefed and know the dangers and are reasonably skilled.”

Whales frequently strand in the shallow tidal waters off Farewell Spit.

- dpa