Pippa Middleton has turned down big stateside opportunities to promote her new book "Celebrate" because she's afraid she will be asked about her sister Kate Middleton's topless scandal. 

Promoting her book, which is about party planning, could have generated a whopping $600,000, but Pippa's afraid she'd say the wrong thing and upset her sister, Prince William and the Queen. 

A source told the New York Daily News, "Pippa has been besieged with offers from everyone in the U.S. media offering her a raft of opportunities," which is said to have included "Entertainment Tonight" as well as interviews with Ellen DeGeneres, Oprah Winfrey and Anderson Cooper.

But if she did promote her book, her motives would come into question and it would be suggested that she was using the royal family to gain exposure. 

"If she were seen using the royal family to promote her book, she would soon be viewed as the next generation's Sarah Ferguson," the New York Daily News source explained. "If Pippa is quizzed about Kate's topless pictures, then whatever answer she gives will generate more news about the matter, and upset Will and Kate."

Her book "Celebrate" is due out this month and her publishing house, Viking Press, is disappointed that Pippa is not participating in a book tour. 

"Viking [Press] was hoping that there would be a huge swell of publicity for this book which would lead to sales," the New York Daily News source said. "Nobody has really ever heard Pippa speak before and U.S. audiences are fascinated by her. This could have launched a new lucrative career here."

The publishing houses' spokeswoman, Lindsey Prevette, confirmed that Pippa is not doing any publicity for "Celebrate."

"Pippa is not doing anything for us. She is not coming here to do interviews and is not available for anything, unfortunately."