Kelly Osbourne has told Paris Hilton to "grow up".
The 'Fashion Police' host lashed out at the socialite following an incident at the Coachella Festival in California this weekend, which saw the 29-year-old presenter and her friends approached by Paris at an informal VIP area, only for things to quickly turn sour.
Paris reportedly glared at Kelly and stormed off after branding her a "b***h", prompting her former pal to last out on twitter.
In a post which has since been deleted, Kelly wrote: "Please grow up, there is no need to act like a child you could of joined us it's not 2005 no one cares. (sic)"
The pair are said to have continued the row in private, and Kelly believes Paris, 33, was just "attention seeking".
A source told the Daily Mirror newspaper: "As far as Kelly is concerned, this is something out of nothing. Paris is being ridiculously sensitive and attention-seeking.
"Kelly was sitting with some friends, minding her own business, when Paris suddenly started bitching and moaning, and slagging her off.
"She was asked by someone else to join the group, but declined and swanned off. The pair didn't speak for the rest of the weekend."
The pair have previously clashed in the past, with Kelly branding Paris a "bad influence" on young girls eight years ago.
However, they later made up, though Kelly admitted she didn't trust her friend with her secrets.
She said: "We have fun together. I know that whatever I tell her, she tells everyone anyway, but I've always known she's not the friend that you tell your deepest secrets to.
"She's a fun person, and there is a sincerity about her."