30 October 2012 Last updated at 10:37 ET

Polar bear sanctuary on iceberg

Tabular icebergs may give the bears sanctuary from hunting

A hitherto unknown polar bear sanctuary in the Arctic has been discovered by the makers of a BBC documentary.

An estimated 20 of the bears were seen on the Peterman Iceberg in Baffin Bay, 50km off the Canadian coast.

For most of the year, polar bears live on the frozen sea water where they hunt seals.

So the finding challenges received wisdom about where polar bears spend the summer months, when the sea ice melts.

The sanctuary was discovered during the filming of BBC Two's Operation Iceberg.

It had been assumed that polar bears had to move on to the land during the summer, in this case, Baffin Island.

The expedition also mapped changes in Greenland's glaciers

But now it is clear that not all polar bears return to land. Some spend the summer months surviving on large tabular icebergs off the coast.

Presenter Chris Packham commented: "What's there for them is security, and I think they are taking advantage of that. So I think they are living on this iceberg to stay safe, and just wait for the sea ice to come back in."

American biologist and polar bear expert Steven Amstrup said this was the first time he had heard of the bears living in large numbers on a tabular iceberg out at sea.

Dr Keith Nicholls of the British Antarctic Survey was also on the expedition. He said: "In recent years we've been seeing a lot more big tabular icebergs come off the Greenland ice sheet and they're now ending up in Baffin Bay."

Polar bears are hunted by humans on both the mainlands of Greenland and Canada so the icebergs may enable the bears to remain safe from human hunting.

Operation Iceberg is being shown on Tuesday 30 October and Thursday 1 November at 2100 on BBC Two