A member of the world's largest rodent species has given birth to a pup in a British zoo, officials have said.

Lily, the six-year-old mom, delivered her playful capybara pup in front of amazed onlookers at Chester Zoo in northern England, Xinhua news agency quoted the zoo officials as saying on Thursday.

The newborn pup was almost straight away up, running around and swimming. The sex of the baby has not yet been determined.

Chester Zoo/Facebook

Capybaras are often referred to as giant guinea pigs and are found living in small herds on grasslands, in tropical forests and on wetlands across much of South America, where they spend much of their time in water. They can grow up to 1.5 meters in length.

Their scientific name means "water pig", and their bodies have been specially adapted for swimming, with webbed feet and their eyes, ears and nostrils located on top of their heads so they can stay submerged with very little of their body showing, helping them to avoid detection by predators.

"Although not currently listed as an endangered species, the capybara is threatened by illegal poaching for its meat and skin, which can be turned into leather, as well as habitat degradation," said a spokesman at the Zoo.

"We hope that Lily's new arrival will help to bring some attention to the species, which they say is often overlooked," said the spokesman.