An Indian teenager was rushed to hospital with chronic stomach pains only to discover he had had 2.5kg parasitic “twin” living inside him.

18-year-old Narendra Kumar from the state of Uttar Pradesh in northern India is one of only 200 people in the world who have been diagnosed with “foetus in fetu” – a rare condition where one twin is absorbed by the other through the umbilical cord during early pregnancy but continues to live inside.

Mr Kumar had suffered from bouts of vomiting and weight loss for years but it wasn’t until they operated on Monday they found the mass of skin, hair and teeth leaching off his blood supply.