Pussycat Dolls singer Ashley Roberts said she and the group have had little contact with Spears as they support her on her Circus tour of the US and Canada.

She said: "Unfortunately there isn't much time for us to hang out. We pop into our dressing rooms, change into our outfits and then go straight out on stage.

"I've seen her in passing through the hallway but she kinda keeps to herself and so do we."

Roberts also admitted that Spears has been outshining her special guests in the fashion stakes thanks to some daring choices.

She added: "Britney is totally outdoing us on outfits. She has some outrageous costumes and I definitely think between us we've taken every rhinestone that's ever been made.

"It's amazing to be supporting her. She's out there every night doing her thing and we feel so lucky to be a part of that."