The oldest and most primitive of Britain's ponies, the Exmoors, are branded as foals in order to identify the semi-feral livestock and prevent them being stolen.

However from this year all horses and ponies have to be fitted with microchips under new EU rules.

Animal rights organisations say the "cruel" practice of branding must now end. But farmers and breeders say branding in still a necessary part of ensuring the purity and health of the breed.

There are around 400 Exmoor ponies running wild in Britain. The ponies, that are owned by different farmers, are rounded up once a year and new foals are branded.

But Cilla King, of People 4 Ponies, said the cruel practice is no longer necessary since all ponies have to be microchipped from this year: "They are fighting for their lives when it is their first experience of humans," she said.

However Sue McGeever, Secretary of the Exmoor Pony Society, said branding was important for maintaining the purity of the breed and health of the animals.

She said Europe had given the UK special permission to allow Exmoor ponies to be branded as well as microchipped: "In the moorland situation being able to identify the pony by brand means that we can keep an eye on the bloodline by seeing which mares are breeding. Also there is a problem with ponies being hit by cars or injured and wandering across the moor. We need to be able to read the brand so that the farmer who owns the pony can give it help."

Rex Milton, a farmer who runs ponies on Exmoor, also said it was a necessity: "It is in the best interests of the Exmoor ponies to be identified correctly. A microchip is impossible to read at 25 metres but it is easy to spot a brand," he said.