A ‘parasitic’ twin has been found in the stomach of a three-year-old boy in Peru.

Doctor Carlos Astocondor, of the medical team at Las Mercedes Hospital, said the 25-centimetre foetus weights 680 grams, has some hair on the cranium, eyes and a few bones.

When the foetus was absorbed by the other foetus inside the mother’s womb, its brain, heart, lungs and intestines never developed, Dr Astocondor explained.

According to Dr Astocondor, the condition, known as 'Foetus in foetus', occurs in about one of every 500,000 live births.