( L - R ) Madonna Timberlake- Reuters

Justin Timberlake is writing songs for Madonna.

The Grammy award-winning star has revealed he is collaborating with Madonna on her new album, and was in a London studio with her on Tuesday.

Justin told Britain's The Sun newspaper: "I have been working on some new music. But it's not for myself - I'm writing for other people. I'm working on some stuff for Madonna."

The 'SexyBack' singer is in London preparing for the UK leg of his world tour.

Madonna, who has continuously reinvented herself throughout her career, is reportedly asked for her new LP to have an R&B influence and has also enlisted the services of top producer Timbaland.

Wants to help Britney

Timbaland has masterminded hits for Justin and Nelly Furtado and is desperate to help Britney Spears relaunch her career.

Madonna, 48, will headline this summer's Live Earth concert in London.