A 12-metre, 45-tonne dead male sperm whale washed up on the Paraparaumu Beach in Kapiti Coast, New Zealand on Wednesday. A whale expert said the mammal probably died after suffocation.

Anton van Helden, collection manager of marine mammals of Te Papa Museum, opined the dead whale is probably an old one based on wear on its teeth and scarring around its head.

Mr Helden said that the sperm whale is the world's largest-toothed predator. The Cook Strait is one of their year-round habitats.

He said no post-mortem examination will be performed on the whale, so the cause of its death would not be known.

The carcass attracted hundreds of people who touched the dead mammal and had their souvenir photos taken. The Kapiti Coast District Council later cordoned the area near the dead whale due to health risks.

Kaumatua Don Te Maipi, a resident, linked the whale's death to the demise on Tuesday of Bruce Mansell, a prominent local resident and the managing director of Coastlands.

There had been previous sightings of dead whales in other New Zealand beaches such as this one.