Caleb Followill is "devastated" after smashing his favourite guitar in a fit of temper.
A source said: "He was livid about the sound and took out his anger on stage without considering the consequences. His guitar is now ruined. The crowd were oblivious to the sound difficulties but the Kings want every show to be perfect."
After smashing the instrument on stage on Friday (10.07.09), the 27-year-old frontman tossed it into the screaming crowd and stormed off.
Off stage, the group were said to have had a furious argument, which saw their tour manager have to drag Caleb away from the rest of the band.
The source added: "When they came off stage, tempers flared and they were shouting and swearing at each other. It was really nasty before their tour manager stepped in. They were even threatening to pull out of Oxegen."
Despite their disagreements, the quartet went on to headline Dublin's Oxegen music festival on Saturday (11.07.09.).