At least 13 pilot whales were beached Tuesday on a remote New Zealand coastline and conservation officials were desperately battling to prevent another 50 from reaching the shore.

It is the second mass stranding in a week at the remote Farewell Spit, at the top of the South Island, which has become notorious as a whale graveyard.

Department of Conservation officials said they were alerted to the latest stranding late Tuesday morning and were using a boat to try to shepherd the whales still afloat out to sea.

Volunteers were protecting the stranded whales from the sun until an attempt to refloat them at the next high tide.

"We plan to attempt to refloat the stranded whales in the incoming tide tonight," conservation ranger Gregg Knapp said.

"We are hoping we can get them afloat and further out to sea before dark when it would become unsafe for people to work in the sea trying to refloat the whales."

Pilot whales are the most common species of whale seen in New Zealand waters.

Last week, a pod of 39 died after a mass stranding in the same Farewell Spit area, about 150 kilometres (93 miles) from the tourist city of Nelson.

Mass pilot whale strandings are common in New Zealand, particularly at Farewell Spit, with scientists unclear about why the marine mammals swim ashore in large groups.