Hackers have placed photos of child pornography on a website run by an Austrian anti-Holocaust organization as the country commemorates the end of World War II.

Interior Minister Johanna Mikl-Leitner has ordered a criminal investigation and condemned the "sick, criminal attack."

The web pages of the Mauthausen Memorial Site were up again Friday after the offensive content was removed.

The organization is charge of maintaining as a memorial the Mauthausen concentration camp in western Austria. Hundreds of thousands died at the main camp and its subsidiaries.

Austria was annexed by Hitler's Germany in 1938. Over the decades, Austrian public opinion has slowly shifted from considering the country a victim of the Nazis to recognition that it was complicit in the regime's crimes.