Elton John attacks Janet Jackson for lip-syncing

Sir Elton John has stunned fans by launching a scathing tirade against Janet Jackson, accusing his fellow superstar of duping fans by lip-syncing on tour.

The R&B icon, 49, launched her music comeback last year (15) with the release of Unbreakable, her first album since 2008's Discipline, and then hit the road for the Unbreakable World Tour.

The live shows, her first in four years, kicked off in Vancouver, Canada in August (15) to great reviews, but Elton can't understand why everyone raved about the concerts, because he's convinced Janet no longer sings live.

"You know, f**king music magazines writing a review of Janet Jackson saying, 'This is the greatest show - four and a half stars,'" the outspoken Brit told Rolling Stone magazine. "It's f**king lip-synced! Hello! That's not a show!"

"I'd rather go and see a drag queen," the 68-year-old declared, before adding, "F**k off."

Representatives for Janet, who recently had to halt her trek to undergo throat surgery, have yet to comment on Elton's harsh critique, but the Candle in the Wind singer is well known for his blunt and brutally honest opinions.

He famously attacked his former foe Madonna back in 2004, accusing her of miming her way through shows, after she was nominated for the Best Live Act honour at Britain's Q Awards.

"Madonna, Best Live Act? F**k off," Elton told the shocked audience. "Since when has lip-syncing been live? Sorry about that, but I think everyone who lip-syncs on stage in public, when you pay like 75 quid (pounds) to see them, should be shot. Thank you very much. That's me off her Christmas card list, but do I give a toss? No."

The pair has since made amends after years of petty fighting, and now Elton admits the Queen of Pop didn't deserve the vitriol he threw her way.

"I say what I feel," he continued to Rolling Stone. "I probably went too far with Madonna, and I got very personal and I wrote her (to apologise) - she was very gracious."