Naturalist Sir David Attenborough is to reveal the first filmed sighting of a rare reptile from his beloved Galapagos Islands in a new TV series.

The veteran broadcaster caught the pink iguana on film while he worked on his new Sky series Galapagos 3D, and it will be the first time the creature has been seen on screen.

The species was only discovered in recent years, and Sir David said it was a privilege to spot the Penny Black of the natural world.

He filmed on the island of Isabela in June last year and his team was led by Dr Gabriele Gentile from Rome's University Tor Vergata as they sought the Conolophus Marthae iguana, which is noted for its unusual pink complexion.

Sir David said: "It's a remarkable thing. A little periwinkle or something which nobody has identified before, is one thing, but this is more than that, it's a large pink iguana. I used to collect stamps, and this was a Penny Black of the natural world.

"It was a privilege to see it," added Sir David, who first visited the Galapagos in 1978 while working on his groundbreaking Life On Earth series.

Executive producer of the new series Anthony Geffen said: "When he finally came face-to-face with the iguana it was just one of the most extraordinary moments that I've ever experienced."