Two Australian tourists have been killed after they were crushed by tonnes of ice collapsing from a glacier in New Zealand.

Police said the two men, who were brothers, ignored safety barriers and approached the face of the popular Fox glacier on the west coast of New Zealand's South Island to take photographs.

The body of one of the men, 24-year-old Ashish Miranda, was recovered on Friday but rescuers have not been able to reach his brother, Akshay Miranda, 22, although he is presumed to also have died.

Rescuers said some of the ice blocks under which he was buried were the size of large vehicles.

The two men were killed when an estimated 100 tonnes of ice from an unstable overhang collapsed on top of them.

The Fox and a neighbouring glacier are popular tourist attractions, attracting more than half a million visitors a year.