Robbie upset about Christina

Robbie Williams is desperate to make peace with Christina Aguilera after slamming her in his autobiography.

The star made some less that complimentary remarks about the singer in his book Feel and now regrets allowing them to be published.

The 30-year-old wrote in his book, "She looks like a cross between someone in a gay club at six in the morning and someone's who's trying to save trees."

Now that he spends most of his time in America, Williams is trying to make amends, he said: "I deeply regret slagging her off. I hope a personal letter can mend bridges between us."

Williams may have been bearing a slight grudge against Aguilera at the time of writing because she turned down the opportunity to duet with him.

Aguilera said of the offer, "I find him charming but our styles are too different. It wouldn't work. He should try Mariah Carey - she likes duets."