The area of collapse measures about 415 sq km - almost two-thirds the size of Singapore - according to satellite imagery from the University of Colorado's National Snow and Ice Data Centre.

The Wilkins Ice Shelf is a broad sheet of permanent floating ice spanning about 3,000 sq km of the rapidly warming south-west Antarctic Peninsula, about 1,600km south of South America.

'Block after block of ice is just tumbling and crumbling into the ocean,' said Dr Ted Scambos, lead scientist at the National Snow and Ice Data Centre.

'The shelf is not just cracking off and a piece goes drifting away, but totally shattering. These kinds of events we don't see very often.'

He said a large part of the shelf is now supported by only a thin strip of ice.

In the past half century, the Antarctic Peninsula has witnessed a warming as fast as anywhere on the planet,.

And Dr Scambos said: 'The warming that's going on in the peninsula is pretty clearly tied to greenhouse gas increases.'

REUTERS