An iceberg roughly a quarter of the size of Wales is about to break off from Antarctica.

A vast area of Larsen C ice shelf - the most northern major shelf in the Antarctic Peninsula - is said to be "hanging by a thread".

Forecast to be one of the largest separations of its kind, the frozen mass has an area of 5,000 square km (1,930sq miles).

An expanding rift, which has increased in size by 18km (11 miles) over the last few weeks, means the piece is now holding on by a strand of just 20km of ice.

The iceberg will be 350m thick when it caves.


Image: The edge of the Larsen C ice shelf meets open water and sea ice

Researchers believe the shedding of the shelf will lead to global sea levels raising by 10cm and could lead to the wider break-up of Larsen C.

The MIDAS Project, based at Swansea University, has been monitoring the rift and is predicting it will shed over the next few months, depending on weather conditions.

Project leader and glaciologist Professor Adrian Luckman, told Sky News: "This is going to be a big change to the geography of the Antarctic Peninsula."

He went on, "There's no need to worry about this, but we have to keep our eyes on these things".

Other shelves have broken away from the Antarctic Peninsula - Larsen A ice shelf in 1995 and the Larsen B in 2002.

In the 2002 breakaway, the National Snow and Ice Data Center said the Earth had lost a major feature that had "likely existed since the end of the last major glaciation 12,000 years ago".

Image: Scientists fear the effects the melting ice will have on sea levels

When asked if global warming had played a direct part in the growth of the rift, Prof Luckman explained: "We can't pin this one on climate change, this is a natural action of a rift that has been there for many years".

However, while he said there was no evidence to "directly" link the Larsen C fissure with climate change, he conceded that "up until the late 1990s the Antarctic Peninsula was one of the fastest warming places on earth.

"It's unlikely that this would have held back the rift. It will change the shape of the landscape".

There is concern that further shedding of ice shelves around the frozen continent due to rising temperatures will lead to raising world sea levels.