This report by Robert Piggott contains exclusive pictures of the ice shelf

Observations made by satellite show that a 75 square mile (200 square kilometres) chunk of the Larsen B ice shelf has recently broken off. An image taken on February 26 showed that much of the ice had gone.

David Vaughn, from the British Antarctic Survey, expects more shelves to break off

The satellite pictures confirm earlier studies made by the British Antarctic Survey that predicted the ice shelf was nearing its stability limit.

"This may be the beginning of the end for the Larsen Ice Shelf," said Ted Scambos, of the National Snow and Ice Data Center in Colorado.

The satellite image taken on March 23

"This is the biggest ice shelf yet to be threatened," he added "The total size of the Larsen B Ice Shelf is more than all the previous ice that has been lost from Antarctic ice sheets in the past few decades."

Scientists believe that the Larsen shelf will continue to crumble rapidly from early next year. No more reduction is expected until summer ends in Antarctica in late December.

Antarctic peninsula ice shelves have been in rapid retreat for the past few decades, apparently in response to regional warming.

Scientists blame climate change, with temperatures around Antarctica rising five times faster than the global average. Experts say the breakaway chunk will not have an immediate effect on sea levels as ice shelves are already floating in the sea.

A spokeswoman for the British Antarctic Survey said: "What we've been observing is that the Antarctic peninsula is experiencing a regional warming but it's not happening in the rest of the continent."

In early 1995 a smaller ice shelf, called Larsen A, completely disintegrated during a single storm after years of shrinking.

"Ice shelves are good indicators for climate change since they respond to change within decades," said Ted Scambos.

Some scientists believe that global warming will result in the total loss of all Antarctic ice shelves within a century or two.