Auckland: More than 20 pilot whales are reported to have died in a mass stranding at a remote beach on New Zealand's South Island.

According to conservation group Project Jonah, 32 whales stranded on the West Coast beach south of Haast on Wednesday with only 11 remaining alive when discovered.

The group said in a Facebook post they were still awaiting further information because the remote location meant there was limited access to communications.

Another post showed photos of people working to keep the whales alive until they could be refloated on an incoming tide.