Scientists at the University of Tübingen found documents at the Dachau concentration camp which detail tests on mosquitoes to see how long they could be kept alive – with a foresight to releasing them on groups of people.

Dr Klaus Reinhardt led the study, uncovering that staff at Dachau's entomology institute had by 1944 decided on a specific breed of mosquito most suited to a potential biological attack, Spiegel reported.

Questions raised in the documents show the problems the Nazis were facing to carry out their plan such as how long mosquitoes could live without food if they were to be transported from a breeding centre to an attack site.

Reinhardt and his team published their findings in the Endeavor scientific journal in December. It states how in 1942 head of the SS, Heinrich Himmler, set up the Dachau entomological institute to study the physiology and control of insects that inflict harm to humans....