While there is no doubt that superstar Mariah Carey can sing among the best of them, some viewers of Sunday's 2013 BET Awards show have accused the singer of lip-synching during her performance of her hit song "Beautiful," Fox News Latino reports.

Some viewers pointed out via Twitter that you could still hear Carey's vocals during a moment when she stopped moving her lips. "I don't even understand why Mariah Carey even came to the BET Awards. She lip-synched the entire time," one viewer wrote.

Carey took to the stage wearing a stunning strapless white dress with a glimmering train, showing off her newly slimmed-down figure while performing alongside Miguel and rapper Young Jeezy.

Carey's camp has yet to address the lip-synching allegations, but this was not the first time Carey was accused of not singing live. During her performance on "American Idol" this year, critics on Twitter slammed the star for lip-synching during her medley of hits.

'Hahaaa Mariah Carey's Idol Finale Performance Could Be The Worst Lip Syncing Of All Time,' wrote @FSBigBob at the time, while @Joey O'Hern tweeted: 'Mariah, you look great...but your lip-synching was off. Good try though!'

According to the Daily Mail, a Hollywood music producer and audio engineer who studied Carey's performance said it was a "tough call," though said bad video editing during the filmed recording could have made it seem as though she were pretending to sing live.

"At around 2:15 to 2:21 in the clip she appears to be out of sync with the audio," the producer told the Daily Mail. "That's the one spot I think could be the giveaway that she's lip syncing,' said the producer at the time, who requested not to be identified. However, sometimes a slight delay in the audio sync to the video can also make someone look like they are lip syncing when they are not. It could just be a bad edit."

Do you think Mariah Carey was lip-synching during her performance of "Beautiful?" Watch the video below and then judge for yourself.

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