Singer Nicki Minaj arrives for the 2012 MTV Video Music Awards in Los Angeles, September 6, 2012.[Photo/Agencies]

Controversial rapper Nicki Minaj and country singer Keith Urban joined the "American Idol" judging panel on Sunday, as the ageing Fox show seeks to boost its star power and recapture sliding audiences in a crowded TV talent show field.

In a decision that divided "Idol" fans, Minaj, 29, known for her outlandish outfits and headline-making performances, and Urban were confirmed by Fox hours before auditions in front of judges kicked off in New York for the show's 12th season.

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They joined Grammy-winning singer Mariah Carey, whose name was announced in July, and record producer Randy Jackson - who with host Ryan Seacrest are the only remaining members of the original line-up.

The new line-up follows the departures earlier this year of Aerosmith frontman Steven Tyler and singer-actress Jennifer Lopez after two years, and returns the singing show to a four-person panel last seen in 2010.

The Fox announcement followed months of rumors about likely contenders for the job, including rapper Kanye West, pop star Katy Perry, Latin singer Enrique Iglesias, former "American Idol" runner-up Adam Lambert, and teen idols Nick Jonas and Miley Cyrus.

"American Idol" has been a ratings juggernaut since it debuted on Fox in 2002 but audiences are now only about half the more than 30 million who watched regularly in the show's 2005 and 2006 heyday.

The last season finale in May drew a record low of 21.5 million viewers and "Idol" lost its eight-year crown as the most-watched program on US television to "Sunday Night Football". The 12th season will start broadcasting in January 2013.

Competition in the TV talent show market has increased dramatically in the last year with the hiring of pop star Britney Spears for a reported $15 million salary for "The X Factor" on Fox, and radio DJ Howard Stern for NBC summer hit "America's Got Talent".

FAKE POPES, ALTER-EGOS, EXPLETIVES

Fox reality programming chief Mike Darnell said "Idol" now boasts "one of the most exciting judging panels around".

"Nicki's an unbelievably captivating international phenomenon who has made an indelible mark on rap and pop. And Keith is ... one of the biggest stars in country music and I know that our fans and contestants will fall in love with him," Darnell said in a statement.

Minaj is the top female rapper in a hip-hop world dominated by male artists. She burst onto the music scene in 2010 and quickly made a name for herself by adopting numerous alter-egos and with multiple hit records including "Starships".

She has also proved controversial, appearing on the Grammy awards red carpet in February with a fake pope. She made headlines last week for expletive-filled lyrics that appeared to support US Republican contender Mitt Romney, but which she later said were meant to be sarcastic.

Reaction to Minaj on Sunday was typically extreme, with some viewers saying they would never watch "Idol" again and others giving a big thumbs up.

"Nicki is a judge on American idol this year watch them ratings go all the way up," wrote Montrell on the official AmericanIdol.com message board.

"Well American Idol has lost this viewer and his family. Nicki Minaj is a disgusting choice to judge any talent show," wrote user Sheavendoor83 on the Entertainment Weekly comments page.

New Zealand-born Urban, 44, is married to Oscar-winning actress Nicole Kidman and is a four-time Grammy winner with sales of 15 million albums.

"SO excited to be joining the team on ?@AmericanIdol!!!!!!" Urban tweeted on Sunday.

According to industry website The Hollywood Reporter, Minaj will get about $8 million, with Urban collecting around $4 million. Carey, one of the world's top recording artists, is said to be getting $17 million, making her the highest-paid celebrity judge on television.

But celebrity judges don't always guarantee success. Audiences for Fox's revamped "X Factor" were down about 3.5 million viewers from 2011 when the show returned last week, despite the addition of Spears and singer Demi Lovato.

"X Factor" was beaten by NBC pop contest "The Voice", boasting judges Christina Aguilera, Adam Levine, Cee Lo Green and country star Blake Shelton. "The Voice" will also get a spring season in 2013 that competes with "Idol" for viewers.

Fox is a unit of News Corp and NBC is majority-owned by Comcast.