LOS ANGELES (Reuters) - "American Idol" executive producer Nigel Lythgoe came out fighting against rival TV shows on Tuesday, calling singing contest "The Voice" a "gimmicky" show and making clear he was fed up with defending "Idol"s slipping ratings.

Speaking to reporters following headlines of bumper audiences for this week's return of NBC's "The Voice," Lythgoe questioned whether other TV talent shows would still be around in 11 years or produce top-level stars such as those that have emerged from Fox television's "Idol".

"After 11 years I am thrilled with these ratings," Lythgoe said. "Of course there is going to be viewer fatigue. It is the same as too many sci-fi dramas or too many hospital dramas. But after 11 years, I don't think we should be defending ourselves."

Roughly 19.7 million U.S. viewers watched last Wednesday's episode of "Idol", which has seen a 20 percent audience decline since its return to TV in January and is fighting to retain its crown as America's most-watched TV show.

By contrast, the second season premiere of "The Voice" was watched by 37.6 million Americans immediately after Sunday's Super Bowl. Some 17.7 million -- a 50 percent increase over last year's debut -- returned for Monday's regular episode in the biggest challenge yet to "Idol's" supremacy in its genre.

"We have survived for 11 years and whatever bad press we are getting about these ratings -- God! the rest of the world would love these ratings," a clearly frustrated Lythgoe said.

He added that there would be no major changes to the "Idol" format as it enters its popular Hollywood round this week.

"Why on Earth would we start looking at other things to put in there? I have no idea...'American Idol' is now in the history books and will remain there. And let's hope all the other shows like 'X Factor' and 'The Voice' continue to be successful for 11 years...I will keep my fingers crossed for them," he added.

Lythgoe said "The Voice" had a "fun format," in which judge-mentors Christina Aguilera, Cee Lo Green, Blake Shelton and Adam Levine initially turn their backs on contestants before competing among each other to mentor the new talent to stardom.

But he added: "It is very gimmicky which is interesting at this time. I particularly like the relationship between Blake and Adam. Other than that, I think they need stronger talent."

Lythgoe was just as dismissive of Simon Cowell's glitzy "The X Factor", saying its arrival on U.S. TV last fall "feels like two 'Idol' singing seasons (a year) on Fox."

He claimed it was "Idol" that was turning out true stars like Grammy winner Kelly Clarkson, who has been hired as a mentor on "The Voice," and Katharine McPhee, a 2006 "Idol" runner-up who is now starring in NBC's musical drama "Smash".

"If what you want is real good talent without gimmicks, without fireworks going off and without flashing lights, and just bloody good talent on the stage, then watch 'American Idol' because that is what you are going to get," Lythgoe said.