The Heard Island and McDonald Islands Marine Reserve - 4,000 kilometres (2,485 miles) off the south-west coast - will be twice the size of Switzerland and will protect one of the world's most unspoilt environments from exploitation.

A number of important species live in the freezing Antarctic waters, including the endangered southern elephant seal and the sub-Antarctic fur seal.

The conservation group World Wide Fund for Nature says it plans to nominate the Australian Government for the Gifts to the Earth Award - its highest recognition for conservation.

BBC science writer Corinne Podger says that no foreign species have yet been introduced to the two islands and no commercial fishing is carried out there.

The region was put on the World Heritage List five years ago but the Australian Government's move to make it a fully protected national park will officially ban fishing, as well as oil and mineral exploitation.

Even scientific research will be limited.

Climate monitored

Australia's Environment Minister, David Kemp, said dozens of species of plants, birds and mammals would be protected.

"The declaration would preserve for science, and for nature, a very large area of one of the most pristine environments left on Earth," he said.

Mr Kemp said the reserve would also allow researchers to monitor the effects of climate change and pollution.

A group of the world's leading marine scientists has previously called for 20% of the world's oceans to be turned into protected marine reserves to save large numbers of fish and other species from the threat of extinction.

The wildest place on Earth - a smoking volcano under a burden of snow and glacial ice rising above the world's stormiest waters

David Kemp, Environment Minister

The size of the new park at 6.5 million hectares (16 million acres) surpasses Australian's Macquarie Island reserve at 5.8 million hectares (14.3 million acres) about 1,500 km (930 miles) off Australia's south-east tip.

Heard Island has Australia's only active volcano, Big Ben, which is also the country's tallest mountain, rising 2,745 metres (9,006 ft) above snow and glacial ice. The island is home to vast numbers of penguins and seals.

McDonald Island has such a steep coastline that only two successful landings have been made by boat since it was discovered more than a century ago.

Mr Kemp described the islands as "the wildest place on Earth - a smoking volcano under a burden of snow and glacial ice rising above the world's stormiest waters".

Two species of the albatross will be protected in the new reserve.

The seas contain soft corals, glass sponges, giant barnacles and endangered species including the Patagonian toothfish, also known as Chilean sea bass, which is prized in restaurants in Japan, North America and Europe.

The Australian Government estimates that poachers harvest more than 2,200 tonnes of the fish each month from southern waters.