British songbird Lily Allen will need bigger breasts if she wants to duplicate her success across the pond in the United States.

The “Fear” singer is furious after being told to undergo breast augmentation in a bid to crack the American music market, Closer Magazine snitches report.

A source says: “Lily’s real hang up is about her boobs. She dropped so much weight in the last six months and it left her almost flat-chested, which has made her feel miserable.”

“Before one of her US shows, someone suggested a really great plastic surgeon to her, saying she needed bigger breasts if she wanted to make it as a pop star. “Lily was furious,” the insider adds, “Saying she would never be so stupid as to have surgery.”

But the tabloid spies fear Lily may be singing a different tune now that fashion legend Karl Lagerfeld has tapped her to front the ad campaign for his Autumn/Winter collection of Chanel Handbags.

“Later, she started asking about the different types of boob jobs.”