The War of the Heiresses rages on! Kelly Osbourne and Paris Hilton have been sporadically friendly toward one another, but it seems like these two Hollywood princesses are back on the "outs" after an unfortunate run-in at Coachella.

And it appears this is no idle gossip, as Kelly herself tweeted about the incident.

"@ParisHilton, please grow up," the Fashion Police co-host wrote on April 13. "There is no need to act like a child. You could [have] happily joined us! It's not 2005. No one cares!"

For her part, Paris responded on Twitter on April 14, pleading ignorance: "@KellyOsbourne, getting tweets about us. I'm confused, as I did not see you once this entire weekend. No clue how these stories get invented."

The Daily Mirror (via Daily Mail) claims to have details from Paris and Kelly's icy encounter at the music festival.

"Kelly was sitting with some mates, minding her own business, when Paris suddenly started bitching and moaning and slagging her off," a source tells the British tabloid. "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."

Kelly and Paris's drama stretches back at least eight years. In 2006, Ozzy Osbourne's daughter deemed Paris a "bad influence" on young girls. Around the same time, Pari's then-boyfriend, Stavros Niarchos, reportedly ruined Kelly's 21st birthday party by trashing her Las Vegas hotel suite.

Looks like old grudges die hard!

Source: Daily Mirror (via Daily Mail)


Credit: AOL Photo: Kelly Osbourne Tells Paris Hilton to "Grow Up" (VIDEO)
Dan Clarendon is an assistant editor at Wetpaint Entertainment. Follow him on Twitter and Google+!