LOS ANGELES, California (X17online) - Madonna may be planning to join Britney Spears on her upcoming world tour, the UK's Daily Mirror reports.

According to the paper, Madonna will appear on stage with Spears at a few of the pop star's upcoming performances in support of her new CD "Circus."

Although there has been no official confirmation from either camp, the newspaper quotes a source as saying that choreographers have been asked to create an "out-of-this-world" dance routine for Britney and Madonna.

"When Britney joined Madonna on stage for her Hard Candy [Sticky & Sweet] tour it was very sedate. This is going to be a high energy dance routine - getting back to what they are both good at, performing," the source said.