The cameras used for a documentary on polar bears were designed to be as unobtrusive and resilient as possible.

Polar Bear: Spy on The Ice used hi-tech "spy cams" to get as close as possible to the bears during summer in the Arctic islands of Svalbard.

But while they were built to withstand temperatures as low as -40C, in the end most could not cope with the curiosity displayed by their subjects.

Polar Bear: Spy on The Ice is broadcast on BBC One at 2000 GMT on Wednesday 29 December - or afterwards on BBC iPlayer.