Eight million people tuned in to watch centrepiece of popular series
Show has been sold around the world
BBC says: 'Commentary is carefully worded so it doesn't mislead'
The BBC's landmark wildlife documentary was four years in the making and took intrepid cameramen to the ends of the Earth to film.
But now it's been revealed the method used to capture key scenes might send a chill down the spine of Frozen Planet viewers.
Instead of being filmed in a sub-zero natural habitat, the BBC has admitted a polar bear and her cubs that were the centrepiece of the show were caught on camera in a zoo.
The breathtaking footage was watched by more than eight million viewers. It showed a polar bear tending her newborn cubs but the snow was fake and real Arctic shots were mixed with zoo scenes.
The scene was filmed last Christmas in the comfort of a German wildlife park enclosure made of plaster and wood.
Situated beneath the zoo's polar bear enclosure, the den was fitted with cameras shortly before the cubs' birth.
Documentary makers have been accused of misleading the audience into believing the footage was gathered by daring cameramen in the wilderness.
The filming of the moving scene is explained by producer Kathryn Jeffs in a hard to find clip on the programme's website.She said it would be impractical to film the carnivores in the wild, adding: 'They stay in the pole through the winter and the female polar bears actually give birth at the peak of winter.
'The problem for us is that they do it underneath the snow in these dens of ice and there's absolutely no way we can get our cameras down there.'
But during the show Sir David Attenborough's script failed to explain how the key scene was made.
A BBC spokeswoman said today: 'This particular sequence would be impossible to film in the wild.
'The commentary accompanying the sequence is carefully worded so it doesn't mislead the audience and the way the footage was captured is clearly explained on the programme website.
'The series website has been extremely popular with our viewers, who regularly look at it for background information and extra clips from Frozen Planet.
'That segment was on the relevant programme page and the series website is given at the end of each episode.'
Yesterday chairman of the Commons culture, media and sport committee, John Whittingdale, said it was 'hugely disappointing' viewers were misled.
He said: 'My view has always been that all broadcasters should not seek to give viewers a false impression and it is much better if they are entirely open.
'If this was not filmed in the wild it would have been much better to have made that clear in the commentary.
'It's questionable how many people would visit the website and find the video clip which explained the circumstances of the filming.'
More than eight million viewers tuned into the fifth episode from the £16million seven-part series on November 23.
It began by showing genuine footage of a male polar bear scavenging for food during the harsh Arctic winter.
This is not the first time Sir David Attenborough has been accused of misleading viewers in his wildlife documentaries.
In 1997, in the most memorable scene of Polar Bear, Arctic Warrior, a mother bear was filmed giving birth to and snuggling with her newborn cub. Viewers were led to believe the scene took place in the Arctic. In fact, it was filmed in a zoo in Frankfurt, Germany.
In 2001, Sir David was accused of using deceptive techniques in Blue Planet when it included a lobster spawning scene that was filmed in a British aquarium. Viewers were led to believe the scene was taking place off the coast of Nova Scotia.
And in 2008, Sir David was accused of staging a confrontation between himself and a cobra in a South African desert for the series, Life in Cold Blood. By LEON WATSON - dailymail.co.uk