Newly uncovered photographs of Nazi officials and SS officers relaxing away from their duties at the Auschwitz-Birkenau death camp in 1944 have gone on display online.

The 16-page album, given to the US Holocaust Memorial Museum by a former US army officer who found it in Frankfurt in 1946, belonged to an SS officer called Karl Hoecker.

Many of the 116 images were taken at an SS resort called Solahuette, just outside Auschwitz, where guards and officials were sent to unwind as a reward for "good work".

Among those pictured socialising are notorious Auschwitz doctor Josef Mengele (second left), who experimented on prisoners, and officers who ran the death camps.

On the same day Hoecker and SS women were snapped enjoying blueberries, records show 150 prisoners arrived at Auschwitz. The SS selected 33 for work and gassed the rest.

Hoecker, who claimed he did not know about the mass killing of Jews at Auschwitz, is seen decorating a Christmas tree only weeks before Russia's Red Army liberated the camp.

Historians say the images of SS officers enjoying themselves in their time off are not a surprise, given other documentary evidence - but are chilling nonetheless.

Holocaust survivors say they hope the album, while offensive, will remind viewers that the perpetrators of genocide are ordinary people, and act as a warning for future generations.