Relatives and parents of what are known as Spain’s “stolen babies” gathered in Madrid to press once more for their cases to be reopened.

Campaigners believe hundreds of thousands of newborns were taken from parents with leftwing political views by the Franco regime.

Participants in the demonstration expressed their anger. One said: “They have stolen our babies; they have snatched our children from us on the first day or even since their first hours of their live.

A mother told the heart-rending story of what happened to her: “After the birth they told me that my baby had died because his lungs were flooded. But I know it was a lie because I could see him, he was blond and he was alive, he was healthy.”

One thousand five hundred cases have been filed but many have lapsed due to the passage of time or been dropped for lack of evidence.