Hackers have put child abuse images on the memorial website of the Mauthausen concentration camp in Austria, 70 years after the Nazis' WW2 defeat.
The website was quickly deactivated by the company managing it, a message on it reads. The Austrian interior ministry is investigating the attack.
Interior Minister Johanna Mikl-Leitner called it a "criminal, sick attack and deeply abhorrent".
The Nazis killed more than 100,000 people at Mauthausen in 1938-1945.
The camp - one of the most notorious and biggest in the Third Reich - was liberated by US troops in May 1945. On Sunday there will be commemorations of the liberation at Mauthausen.
The exact death toll is not known. Inmates, many of them Jews, were starved, tortured or gassed to death. Others died of exhaustion through hard labour.
Many Soviet prisoners-of-war and Spanish Republicans were also among the victims. Many sub-camps were also set up near the main camp.
Austrian officials suspect that far-right extremists may have carried out the attack, as such extremists have hacked several websites in recent months, Austria's Der Standard news website reports.
The head of Austria's Mauthausen Committee - a group promoting human rights and democracy - condemned the hack.
Willi Mernyi said it was "obnoxious and reveals the mindset of the hackers".