The duo took to social media to share with followers an allegation by a female that she was slapped on the backside by a man while in the audience for the band's concert at London's Brixton Academy last week (ends20Dec15).

The victim wrote a message to the band on Facebook.com, stating, "I was assaulted in the crowd by a man who thought it was necessary to hit me across the a** with both hands... I told him that we don't come to gigs to be groped by idiots like him, and he laughed in my face and told me to lighten up - to him, it was a 'bit of fun'."

Slaves reposted the message alongside a separate note from a father thanking the band's supporters for looking after his teenage daughter at a show.

The band wrote, "Two sides to the story. Thanks to our fans who have respect. The others make me feel sick. If you witness anything like this at our show take a stand and look after your fellow humans. How would you feel if that happened to your mother, sister or daughter? Unacceptable. If you saw this happen at Brixton please speak up."