Jessica Simpson Still With Operation Smile  5/21/07

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Pop star Jessica Simpson has refuted claims she "used" a children's charity to gain exposure.

The singer - who has supported the facial deformities charity for a decade - failed to attend the Operation Smile benefit on 12 May (07) sparking rumors she had dumped them.

A source tells the New York Post, "She's turned her back on them.

"She got a lot of good publicity from the charity but refused to let pictures of her be in the commemorative book and hasn't done anything with them in a year."

But a representative for the singer-turned-actress denied the allegations, claiming she was in Germany being honored at the UNESCO Gala to Benefit Children in Need, "Partly for her work with Operation Smile."

She adds, "Jess was one of four honorees for her philanthropic work. She sang two songs, and the event raised about $3 million to build schools all over the world."