Polish prosecutors on Saturday said they had pressed charges against 11 people who slaughtered a lamb and then stripped naked at the former German Nazi death camp Auschwitz-Birkenau.
The unprecedented stunt, carried out on Friday in front of the camp's "Arbeit macht frei" ("Work makes you free") gate, was apparently intended as a call for world peace.
After killing the lamb, the seven men and four women, all aged between 20 and 27, draped a white banner with "love" written in red over the infamous gate, removed their clothes and chained themselves together.
They used a drone to film the incident, local media reported.
The perpetrators, among them six Poles, four Belarussians and one German, were charged with "desecrating a monument", Oswiecim regional prosecutor Mariusz Slomka said, quoted by the Polish PAP news agency.
The man who killed the lamb will face additional charges under animal protection laws that carry a penalty of up to two years behind bars, he said.
They told police the act was intended to be "a performance, a demonstration, for world peace," he added.
Local media reports had suggested it was intended as a protest against the conflict in Ukraine.
Several of the group were released on Saturday.
Slomka said they had met online and organised the event through social media, but added that there was no evidence they had any political affiliation.
Auschwitz Museum guards at the site intervened immediately to detain those involved, with museum officials saying they were "shocked and outraged" over the "reprehensible act" which marred the memory of the camp's victims.
The museum is located in the southern city of Oswiecim on the site of the Auschwitz death camp which was built by Nazi Germany after it occupied Poland during World War II.
The Holocaust site has become a symbol of Nazi Germany's genocide of six million European Jews, one million of whom were killed at the camp between 1940 to 1945.
More than 100,000 non-Jews also died at the death camp, according to the museum. An estimated 232,000 of the victims were children.