The pop star, who sang with Spears on ‘Me Against The Music’ in 2003, said the singer was “never allowed to have a childhood” because she achieved fame so young.

"She didn’t get to grow up and make mistakes privately... she's been under a microscope since she was a teenager, which I think is really tough, it's hard to evolve that way,” Madonna said, in an interview with the BBC.

Earlier this week, Spears was granted increased access to her two children after a judge in Los Angeles deemed she was making progress in overcoming her problems.

The singer’s erratic behavior has courted the world’s attention since she split with her former husband Kevin Federline eighteen months ago.

Madonna was speaking on the eve of her appearance at One Big Weekend in Kent later today (May 10th).

The singer will headline the festival, which will be broadcast on BBC Radio 1.

(by Jason Gregory)