Kim Kardashian's mother has come to the defence of her son-in-law-to-be Kanye West after the rapper was accused of beating up a man who bad-mouthed his fiancee.

The Stronger hitmaker is at the centre of a police investigation over allegations he assaulted a man who threatened Kardashian after she took offence to racist comments he made to her in a Los Angeles medical building on Monday (13Jan14).

But the reality star's manager mum, Kris Jenner, insists the teenager West allegedly attacked deserved what he got.

In an interview with Australia's 2DayFm, Jenner said, "I do know that how it started was that this person got really... a lot of racial, hateful, horrible things that he was saying (sic), and I think that's where it started. I'm not quite sure how it ended, to be honest with you...

"I think that what happened was that somebody got really out of line. Very hateful person."