German police detain a suspect after fire engulfs Hitler's Eagle's Nest retreat in the Bavarian Alps

A motorcyclist approached officers who were heading to the blaze, and police later detained that person near the scene. Arson is suspected, and prosecutors in Traunstein have taken over the criminal investigation. A police spokesperson said the Kehlsteinhaus near Berchtesgaden is 'unlikely to be salvageable'. Nobody was inside, and no injuries have been reported.

Around 200 firefighters battled flames 1,834 metres up, still burning on Saturday morning.

Spokeswoman Lisa Maier said crews needed 'heavy breathing apparatus' to reach the building.

Nazi commanders met there in 1941 to plan the invasion of the Soviet Union.