Britney Spears could be wrecking her comeback with junk food.

The 'Womanizer' singer is said to be refusing to stick to the 1,200 calories-a-day diet devised for her by her managers and has regularly been bingeing on fast food.

A source close to the singer told Britain's Daily Star newspaper: "Britney's been eating burgers and chips for lunch in complete defiance of the strict eating plan worked out for her.

"It's as if she's trying to defy her father and bosses, and break out of the controlled environment by turning away from the healthy lifestyle they've put in place."

"Every decision in her life is made for her and she's kept under the strictest watch to make sure her comeback is a success. Eating her favourite foods is one of the few ways she can control things."

Britney, 27, has shed 28lbs since July after being put on a strict exercise regime and diet as part of her continuing recovery from a breakdown earlier this year.

However, she recently claimed the strict conditions of her new lifestyle make her feel trapped.

She said: "When I tell people the way I feel, they hear me, but they aren't really listening. I'm sad. Even when you go to jail, there is always the time you know you are going to get out, you know? But in this situation, it's never ending. "

Britney is currently in India, where she has reportedly embarked on a romance with Bollywood dance instructor Sandip Soparrkar.

Sandip is working with Britney on routines for her upcoming world tour.