'American Idol' judges
Mariah Carey (second left) served as a judge in 2012. Reuters

Former American Idol boss Nigel Lythgoe has blamed Mariah Carey and Nicki Minaj for the demise of the talent show.

Following news that Simon Fuller's singing competition would be coming to an end after season 15, he claimed that it went downhill after the two divas were cast as judges.

"Mariah and Nicki were just crazy, and then it really started becoming about the judges and took away from the contestants altogether," Lythgoe told Billboard.

The Hero songstress and Young Money rapper joined the show in 2012 for season 12 (which aired at the beginning of 2013) but their time on the show quickly descended into disaster when the duo fell out during auditions. Their infamous explosive bust-up, which was captured by TMZ, quickly overshadowed the contestants.

Lythgoe, who stepped down as executive producer in 2008 for seasons eight and nine, but then returned in late 2010 for seasons 10, 11, and 12, said that their lethal combination was the final nail in the coffin.

"I think that was a major failing on the part of casting to have those two together. On their own, either one may have been successful."

Earlier in May, Fox confirmed that the show's 2016 season would be it final outing after a 16-year run.

In a statement posted on its website, the network said that the final season would be a "celebratory event" that will see current judges Jennifer Lopez, Keith Urban and Harry Connick Jr make a comback.

"American Idol XV will feature host Ryan Seacrest and judges Jennifer Lopez, Keith Urban and Harry Connick, Jr, as they search for the final Idol superstar and pay tribute to the past 14 seasons of amazingly talented contestants and the millions of fans who tweeted, texted and championed their idols."

Meanwhile, Simon Cowell, who quit the show in 2010 to launch the US version of his show The X Factor, has recalled the good times he had in the judge's chair. He is expected to return for the final hurrah.

"We had a blast! Me, Paula, Randy, Ryan – and not forgetting Brian," he told People magazine.

"Thanks to the fans we were able to make some great shows and found some amazing artists. Fox took a risk on a brand new show and I want to thank them for giving us the opportunity. They really were great times."

American Idol has seen its ratings dwindle in recent years with the rise of shows, including The Voice, The X Factor and America's Got Talent.