Adolf Hitler had a disabled younger brother who died of hydrocephalus when the Nazi dictator was three years’ old, a historian has claimed.

Florian Kotanko said he has discovered documents proving that Hitler had a secret brother who died seven days after his birth after suffering from a build-up of fluid on the brain.

Mr Kotanko claimed that the discovery raised the possibility that at the age of three, Hitler was aware of his mother’s pregnancy and could have been influenced by the possible memory or knowledge of his disabled brother.