ONE of the largest icebergs ever recorded has broken off the Larsen C ice shelf in Antarctica in the past few days, scientists said.

The one trillion tonne 5800sq km iceberg calved off between July 10-12, creating a hazard for ships as it breaks up, scientists at the University of Swansea and the British Antarctic Survey said.

It is 2.5 times as big as the Australian Capital Territory and was more than 10% of the shelf. It is expected to melt "at a rapid rate".

It did not impact sea levels because it was already floating.

But if the shelf starts to retreat significantly and collapse, there will be a contribution to sea level rise, said Professor David Vaughan, glaciologist at the British Antarctic Survey.

"There is little doubt climate change is causing ice shelves to disappear in some parts of Antarctica at the moment," Vaughn said, adding that the disintegration of Larsen C was most likely caused by climate change.

He said though some parts of Antarctica are losing ice to ocean rise, significant warming in recent decades has contributed to ice shelf collapses.