BBC bosses defend techniques used to film Frozen Planet
13 December 2011 Last updated at 15:19 GMT
The BBC has defended filming techniques used in parts of the nature series, Frozen Planet.
There has been criticism of the decision to use footage of polar bear cubs which was filmed in a zoo, without making it clear to the audience.
The Director General, Mark Thompson, and the Chairman of the BBC Trust, Chris Patten, were questioned by MPs at the Culture Media and Sport Committee.