Volunteers were fighting to save the lives of 40 stranded whales on a New Zealand beach yesterday.

Thirty-six pilot whales have already died in the mass beaching but rescuers have managed to refloat 17 others in deeper water.

Department of Conservation area manager John Mason said that the 40 whales they are now trying to save were briefly swimming in shallow water early yesterday but became stranded again by the evening as the tide went at Farewell Spit on the South Island.

Mr Mason said volunteers wouldtry to keep the whales cool and wet until dark.

After that, all they could hope for was that the whales would swim away on the next high tide during the night.

Pilot whales grow to about six metres and regularly strand themselves in large numbers during the New Zealand summer months.

Experts describe Farewell Spit as a whale trap due to the way its shallow waters seem to confuse whales and diminish their ability to navigate.