NEW YORK (AFP) - Kanye West on Wednesday urged an overhaul of the Grammys to award commercially successful musicians, even as the rapper toned down his criticism of this year's surprise winner Beck.

The famously mercurial West stole the spotlight at the music industry's awards night on Sunday when he rushed toward the stage as Beck - the innovative rocker who has enjoyed critical acclaim, if a niche following, for two decades -accepted the Album of the Year award for his lush, melancholy Morning Phase.

Soon after the broadcast, West said that Beck should "respect artistry" and give his award to superstar Beyonce for her self-titled album, one of her most intense works which features the ode to marital bliss Drunk In Love sung with husband Jay-Z.

West on Wednesday insisted that he did not mean to insult Beck, calling the 44-year-old Los Angeles alternative rocker "one of the nicest guys and one of the most respected musicians in the game."

But West, alluding to Beyonce's well-received Gospel-inspired performance at the live-broadcast ceremony, accused the Grammys of "capitalising off the amount of views Beyonce gets for them."

"There has to be some level of respect for the people that they have there to sell advertising for them," he told radio host Ryan Seacrest.

West, husband of the thrice-married socialite Kim Kardashian, compared the Grammys to spouses who "get a divorce with us every year, and break our dreams every year."

The rapper threatened to boycott future Grammys if the Recording Academy, which runs the awards, did not reform the voting process to recognise commercial success.

West has won 21 Grammys, making him one of the most awarded artists ever. He performed at the latest Grammys in a collaboration with ex-Beatle Paul McCartney and R&B singer Rihanna.

He also faulted past Album of the Year awards to French electronic duo Daft Punk and Canadian indie rockers Arcade Fire. But West, who is African American, regretted that his initial remarks were interpreted as implying racism by the Grammys.

"It's not a black or white thing at all. It's not always me standing up for a black artist," he said.

He raised controversy after Hurricane Katrina in 2005 for charging that then president George W. Bush "doesn't care about black people." At the 2009 MTV Video Music Awards, he grabbed the microphone from winner Taylor Swift to say that Beyonce was better.

He said Swift - who has enjoyed massive commercial success with her most recent album 1989 - had supported his intervention at the Grammys and announced, with little detail, that the two planned to record together.

The Grammys, like any award show, are regularly faulted by those who disagree with the results.

The Grammys have long faced the exact opposite criticism of West's, with selective music fans distraught by the prevalence of mainstream acts. During alternative rock's heyday in the 1990s, Album of the Year winners included Celine Dion and Whitney Houston.

The Grammys are awarded through voting by industry professionals. The rival American Music Awards are determined based on popularity and most recently named British boy band One Direction as Artist of the Year.

Beck - whose music has captivated critics with his merging of styles and ironic touches - was diplomatic about West's criticism.

He told Us Weekly that he had expected Beyonce to win and that West "deserves to be on stage as much as anybody."

But Shirley Manson, lead singer of alternative rockers Garbage, lashed out at the rapper.

"In attempting to reduce the importance of one great talent over another, you make a mockery of all musicians and music from every genre, including your own," she wrote on Facebook.

"Grow up and stop throwing your toys around," she said.

Sam Smith - the British soul singer who swept the other top Grammys - said he was "shocked" that Beyonce did not win Album of the Year but praised Beck.