The musician, whose new album ill Manors is due for release tomorrow (July 23), was photographed last week wearing a shirt bearing the name of the band Skrewdriver, a neo-Nazi group.
According to The Quietus, he has now released a statement expressing his regret for wearing the garment, claiming he was ignorant of the band's history.
The statement reads: "I was ignorant to the existence of the band Skrewdriver. I don't listen to music like that so I wouldn't know the names of bands that make that music."
Plan B goes on to explain that he made the shirt using photos from photographer Gavin Watson's book Skins, believing the photo represented the "demonised youth of the past".
He added: "Not all of them were racist but because some of them were, the rest were all tarred with the same brush. That is why I feel the images of the skinheads represented in Gavin's work are relevant to me and this generation.
"Gavin is a friend and the people he took photos of were his friends who listened to reggae and ska music. He documented life in those times, some of the people he shot may have been racists but his family and close friends weren't.
"The boy on the image is Neville Watson. Neville is Gavin Watson's brother. The graffiti behind him is graffiti. Neither Gavin or Neville put it there, it was already there when Gavin took the photo."
The 28-year-old rapper has expressed deep remorse for the T-shirt, claiming that he is angry at himself for wearing it.
"The minute I found out what the words on the T-shirt meant I was angry with myself for not questioning them," he explains. "The T-shirt is not official nor is it on sale anywhere. It was of my own doing and therefore it is my mistake, but that is all it is."