Two rare red pandas are the first of their kind to be born at a zoo.

The twins, male and female, were born at Drusillas Park in Alfriston, East Sussex, and were discovered by head keeper Mark Kenward during his early morning rounds.

Female red pandas are only fertile for just one day a year and can delay implantation until conditions are favourable, a zoo spokeswoman said.

They give birth to between one and four young at a time and the cubs are born with pale fluffy fur.

This darkens to the distinctive red colouration of the adults over the first three months, she said.

Mr Kenward said: "I entered the panda enclosure and was immediately met by Tibao, our male panda.

"Unable to see our female, Mulan, I called to her. She appeared from one of the nest boxes shortly after carrying a baby gently in her mouth.

"She brought the cub over, as if to show me, before returning to the box. I can't explain how happy I was."

The keepers have been keeping a close eye on the new arrivals.

At nearly a month old, the pandas are gaining between seven and 20g a day and have just started to open their eyes.

They will be looked after in the nest box by their mother for a while yet but will soon be venturing out to explore their surroundings, the spokeswoman said.

Red pandas are a relatively new addition to the zoo following their introduction in April 2013.

Tibao and Mulan were paired as part of the European breeding programme arriving from Asson Zoo, France, and Paignton Zoo in Devon.

The creatures normally inhabit the Himalayan mountains of China, India and Nepal, where they are threatened by habitat destruction and hunting.

There are now believed to be as few as 10,000 adults left in the wild, the spokeswoman said.

Mr Kenward added: "I am so proud of Mulan. She is a natural mum and has not put a foot wrong. It is as if she has grown up overnight.

"Tibao has less to do with the babies but he seems to have an extra spring in his step and has definitely grown in confidence."