Dolores Delgado, the Spanish prosecutor for human rights and democratic memory, yesterday announced the launch of the investigation, which will examine whether the Franco dictatorship collaborated with the Nazi regime to detain and transfer Spaniards exiled in France to various concentration camps.

Spanish detainees in the Mauthausen and Gusen camps – regarded as having some of the worst conditions of the Nazis’ concentration camps – were subjected to forced labour, torture, disappearance and murder.

The beginning of the investigation follows an application to officially register the deaths of 4,435 Spaniards, most of whom died in those camps and many of whom have not yet been identified.

“The initiation of these proceedings, which seek to clarify these serious violations of international human rights law and international humanitarian law committed in the context of crimes against humanity, coincides with the 80th anniversary of the liberation of the Mauthausen extermination camp,” the prosecutor’s office said.