American Idol judge Paula Abdul poses at the party for the 12 finalists of the television show "American Idol" in Los Angeles March 5, 2009.[Agencies]

LOS ANGELES - Paula Abdul has decided to quit the top-rated U.S. television show "American Idol," ending weeks of speculation about her future as a judge on the popular singing contest.

Making her announcement on her Twitter feed on Tuesday, Abdul said "with sadness in my heart," she had decided not to return to "Idol" which is due to start auditions for its ninth season within days. She did not give any reason.

Abdul, 47, a singer/dancer turned TV personality, has been a mainstay of the show since it was launched in 2002 and quickly became an audience juggernaut for News Corp's Fox network, growing into an estimated $1 billion-plus brand.

"I'll miss nurturing all the new talent, but most of all being a part of a show that I helped from day 1 become an international phenomenon," said Abdul, who was known for finding something positive in almost every performance.

"What I want to say most, is how much I appreciate the undying support and enormous love that you have showered upon me."

Fox and the show's producers FremantleMedia North America and 19 Entertainment said they were "saddened" that Abdul would not be returning to the show as she had been "an important part of the 'American Idol' family over the last eight seasons."

"While Paula will not be continuing with us, she's a tremendous talent and we wish her the best," they said in a joint statement, also giving no reason for her departure.

Abdul's future with the show had been unclear since the eighth season ended in May with speculation rising as producers locked in new contracts with some of the other key players.

"Idol" producers renewed host Ryan Seacrest's contract last month for three years for a reported $15 million -- triple his previous salary -- with the new season to go to air in January 2010.

This week the show's producers announced songwriter and record producer Kara DioGuardi, who was brought in this year as the fourth judge alongside Simon Cowell and Randy Jackson to boost sliding viewership, would be back on the panel.

But the producers had said nothing about Abdul, whose talent manager said in July that she was upset about not having received a new proposal and might leave the show.

Reports speculated that she was seeking a hefty pay raise while other reports suggested she was unhappy with the way she was being treated.

Cowell, the often-acerbic British judge, has cast doubt on his own future with the show after his contract expires in May 2010 after repeated comments that he was getting bored with it.

Jackson's contract also expires in 2010 but he has not publicly indicated his wishes.

Despite sliding viewership, "American Idol" is still America's most watched TV show, drawing an average 26.3 million viewers to each episode in the last season that ended in May.

"American Idol" is seen in more than 100 countries and is a joint production between 19 Entertainment, a unit of CKX Inc, and FremantleMedia, a unit of British-based RTL Group, which is controlled by media giant Bertelsmann AG.