Slowing population growth is key to protecting the planet, Sir David Attenborough has said.

In an interview with BBC Newsnight, the veteran broadcaster discussed the state and future prospects of the world's environment.

The 92-year-old told the programme: "In the long run, population growth has to come to an end. There are some reasons for thinking that will happen almost inevitably.

"One of the reasons that the population has increased as fast as it has is that people like me are living longer than we did. And so there are more and more people just because the expectancy of life has increased."

Sir David told the BBC he has been reassured by a change in attitudes towards the planet, symbolised by the signing of the Paris Agreement in 2015.