BRITISH naturalist Sir David Attenborough has defended an award-winning BBC nature documentary series which sparked controversy when it was revealed that footage it showed of the birth of a polar bear cub in the Arctic was actually shot in a zoo in Germany.

Appearing on ITV1's This Morning program today, Attenborough said, "If you had tried to put a camera in the wild in a polar bear den, she would either have killed the cub or she would have killed the cameraman, one or the other."

"It's not falsehood and we don't keep it secret either."

Frozen Planet, which picked up eight million viewers in the UK and premieres in the US next year, mixed genuine shots of polar bears in the wild with scenes of young bears in captivity in a wildlife park, being tended to by their mother amid piles of fake snow.

Attenborough narrated the scenes, telling viewers that a male polar bear scavenging for food "must live on his resources, this is a time to scrape by," before the documentary cuts to the female polar bear tending her newborn cubs.

Attenborough then adds, "But on these side slopes beneath the snow new lives are beginning. The cubs are born blind and tiny. An early birth is easier on the mother. In two more months polar bear families will emerge on the snowy slopes all round the Arctic."

Only a behind-the-scenes video by producer Kathryn Jeffs posted on the Frozen Planet website revealed the truth about the scenes, a fact originally reported by the Daily Mirror.

"The commentary accompanying the sequence is carefully worded so it doesn't mislead the audience," a BBC spokesman said yesterday.

The spokesman said that Attenborough knew some of the footage was filmed in a zoo, adding, "He knows it would have been impossible in the wild."

However, the UK chairman of the Commons culture, media and sport committee, John Whittingdale, described the "faked scenes" as "hugely disappointing".

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," he added.

Frozen Planet will be narrated by Alec Baldwin for US audiences when it debuts on the Discovery Channel on March 18.

The BBC initially agreed to sell the network only the first six episodes of the seven-part documentary, because it was felt that the seventh episode, which investigates climate change, would not be a hit with US audiences.

The Discovery Channel announced earlier this month that it would air the final episode.