The queen of pop, who infamously kissed Spears at an awards ceremony in 2003, also said she could identify similarities between their careers.

"There's a certain fragility about her and vulnerability about her that makes me feel maternal towards her," Madonna said in a new documentary about the star.

"There are as pects about her that I recognize in myself when I first started out in my career. I also admire her talent as an artist."

Spears recently joined Madonna in Los Angeles as part of her Sticky & Sweet world tour.

In the MTV documentary, Spears described the last three years of her life, which have been played out vividly in the media, as “a really, a really bad time”.

She added: "My trust has really been battered. I'm very wary of a lot of things.”

Spears released her new album, 'Circus', in the UK today (December 1st) - a day ahead of it's release in the US.

(by Jason Gregory)