Franco made secret list of Jews for Nazis

The list was given to Himmler and could have sent thousands more Jews to the concentration camps.

A letter, signed by José Finat Escriva de Romaní, Franco's head of security, was sent to all provincial governors in May 1941, ordering that they identify "all the national and foreign Jews living in the province”.

Himmler called for Jewish converts to Christianity to be included, and asked that the list showed “personal and political leanings, means of living, commercial activities, degree of danger and security category".

The letter called for specific attention to be paid to Sephardi Jews, who were considered to be able to hide their origins because of “their similar temperament” to Spaniards.

This was not the first instance of the Spanish regime working with the Nazis, with Mr de Romaní even taking Himmler to a bullfight in Madrid on one occasion.

Although the Spanish fascists were backed by Hitler and Italian leader Mussolini during the Spanish Civil War, General Franco did not officially join the Axis powers during the Second World War.

The degree of collaboration between the two powers during the Holocaust has been long debated. After the war ended General Franco sought to distance himself from the Nazis.

Some historians have suggested he was of Sephardic descent.