Patrick Carney, the drummer from The Black Keys, has hit out at Justin Bieber's attitude after the Canadian sensation tried to set his 40 million Twitter followers on him for remarks he made about the pop star's lack of success at the GRAMMY Awards.

The feud began last year after Carney told reporters that Bieber shouldn't feel snubbed by the GRAMMYs because he's a rich star: "Grammys are for music, not for the money, and he's making a lot of money. He should be happy."

Upon reading the comments, Bieber then took to his Twitter page and voiced his opinion on the Black Keys drummer, writing: "The Black Keys drummer should be slapped around haha."

Now, Carney has explained to the Rolling Stone that Bieber is an ungrateful and "irresponsible a**hole" who didn't understand that he was complimenting him all along:

"Justin Bieber, like a f**king irresponsible a**hole, sicced 40 million Twitter followers on me because I paid him a compliment he didn't understand. I'm saying that he should be grateful that he has a f**king career in music. And he shouldn't be f**king telling his followers to slap me, and then also be doing anti-bullying bulls**t. It's so irresponsible."

"I mean, Justin Bieber is a f**king moron. And that's the gist of what I was saying. And then he goes and says I should be slapped? Honestly, I feel bad for him. Every single person who works with him should f**king be embarrassed..."

He added: "And honestly, I don't dislike his music. I don't listen to his music, but he needs to not conduct himself that way. Like, really, you make millions of dollars playing music, you should feel f**king lucky".

Watch Carney's initial interview about Bieber below: