Dannii Minogue was stunned when security guards stopped her on the way to see her sister Kylie backstage at a show.
The 39-year-old, who is watched by millions as a judge on The X Factor, told MyDaily.co.uk: "I actually had someone ask me for my pass.
"I did think about putting it on but thought it would be OK to just have someone walk me though."
Kylie added: "I actually think it was because they wanted to pat you down - there were ulterior motives."
In the interview, which Dannii conducted, Kylie confessed to having a shot of whisky before going on stage.
The pop princess, 42, also revealed she does her own make-up on tour.
"I actually don't want it any other way because it's become part of the process of getting ready and becoming that person," she said.