Beyonce Knowles has slammed critics for suggesting she is struggling with a weight issue after she was pictured out in New York showing off a more rounded figure.

The Bootylicious beauty donned a hip-enhancing Thierry Mugler gown in early March and hit the streets of the Big Apple to film a promo video for her I Am... tour.

The dress has attracted unflattering comments about the singer's curvy figure, with some detractors claiming Beyonce's weight is gradually ballooning.

It wouldn't be the first time Beyonce has drastically changed her physique - she piled on the pounds to portray Etta James in 2008 movie Cadillac Records and went on a strict diet to slim down for her role as Deena Jones in the big-screen adaptation of Broadway musical Dreamgirls in 2006.

But the star's spokesperson insists Beyonce is fighting fit as she heads out on tour.

Her representative tells Usmagazine.com, "This is not a weight-gain issue. Beyonce is in the best shape of her life. The exaggerated hips are a design element of a truly couture dress. Beyonce has always loved this dress."

The Mugler couture outfit is one of many designed for Beyonce - the fashion guru was also responsible for creating the 58-piece stage wardrobe she will wear on tour.

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(This news article provided by World Entertainment News Network)