The world's smallest and rarest pig, which was once feared extinct, is to be re-introduced to the wild.

Pygmy hogs were thought to have been wiped out in the 1960's until two small populations were found in Northern Assam (India) in 1971.

A conservation programme that began in 1995 when six were captured for breeding has been so successful that 70 of the 12 inch-tall hogs now fill the holding pens and 10 are to be released into the wild later this year. The breeding program is the only one of its kind in the world. They will be set free in the next dry season, which starts in November.

The breeding scheme has been hugely successful and it is now time to return the hogs to the wild.

The released animals will help to boost the size of the wild population which is still critically endangered, with estimates suggesting that between 100 and 150 are left in the wild.

Despite legal protection, they are still threatened by poaching and loss of habitat to livestock grazing.

The pygmy hogs are kept in enclosures that mirror their natural habitat as closely as possible so that they will be able to survive when released. Their food is buried in the soil so that the pigs have to root as they will on release into their native grassland habitat. In the wild their main threat will be from pythons and Asiatic wild dogs.

The pigs weigh less than 22lb (10kg) each, males are solitary and families of up to 14 travel through elephant grass in single file with an adult female at each end.