A group of students at a US high school dance are being investigated by police after they were photographed displaying what appears to be the Nazi salute.

The photo, which shows more than 50 students from Baraboo High School in Wisconsin taking part in the salute at their prom, was posted to Twitter on Sunday by an account called GoBaraboo. 

“We even got the black kid to throw it up #BarabooProud”,” the photo caption allegedly read. 

The account has since been made private.

The post has sparked international outrage on social media, with Holocaust groups saying they were appalled.

https://twitter.com/LoriMMueller/status/1061964791433048064

“It is so hard to find words,” the official Auschwitz Memorial’s tweet said.

“This is why every single day we work hard to educate. We need to explain what is the danger of hateful ideology rising. Auschwitz with its gas chambers was at the very end of the long process of normalising and accommodating hatred.” 

The school’s district administrator Lori Mueller tweeted on Monday (US time) that the photo posted under the hashtag was “not reflective of the educational values and beliefs of the School District of Baraboo”.

In a statement to parents, she said the photo – in which students appear to “be making extremely inappropriate gestures” – was taken last US spring.

“It was not taken on school property or at a school-sponsored event,” Ms Mueller said.

The Baraboo Police Department is aware of a controversial photo of a group of high school students that has been posted to social media. Officers are assisting the Baraboo School District with their investigation into this matter.

— Baraboo PD (@BarabooPD) November 12, 2018

“The school district is investigating this situation and is working with parents, staff and local authorities.

“If the gesture is what it appears to be, the district will pursue any and all available and appropriate actions, including legal, to address the issue.”

Baraboo Police wrote on Twitter that they were aware of a controversial photo of a high school group having been posted to social media.

“Officers are assisting the Baraboo School District with their investigation,” they said.