Dropkick Murphys bassist Ken Casey has been caught on camera appearing to beat up a fan he spotted giving the Nazi salute onstage at a recent concert in New York.

The incident took place towards the end of the Celtic rockers' show at the Terminal 5 venue last week (13Mar13) after the band invited fans to join them onstage for renditions of Kiss Me I'm S**tfaced and their anti-white supremacist anthem Skinhead on the Mbta.

One fan appeared to get the message behind the latter song all wrong and started raising his arm in the air to indicate he was a neo-Nazi, prompting bass player Casey to march over to the man and allegedly attack him.

Video footage of the confrontation, in which Casey appears to throw punches at the guy, before taking off his guitar and using it to hit him, surfaced online this week (begs18Mar13).

Stepping up to the microphone, he then addresses the situation, telling the crowd, "Nazis are not f**king welcome at a Dropkick Murphys show."