Mariah Carey has been criticised for delivering poor vocals at her Japan show this weekend.

The R&B diva was the subject of several Twitter rants following a lackluster performance in Tokyo Saturday night, marking the first date on her Elusive Chanteuse World Tour.

A video went viral after the gig appearing to show the pop star struggling to hit her notes, TMZ reported.

"It's a wrap for Mariah Carey's singing career," one user wrote, according to UK newspaper The Mirror.

"Mariah Carey should've bowed out right when her voice was giving out. Save herself the embarrassment,' another echoed.

"I see why Mariah Carey never sings live anymore. That's why,' another Twitter user scoffed.

A spokesperson for the singer suggested her team hasn't heard a word of poor reviews.

"The comments we have heard from the fans have been great!" her representative told The Mirror.

The controversy comes amid months of speculation Mariah has been embroiled in an ugly split from husband Nick Cannon, with the America's Got Talent host admitting during a recent interview they have been living apart for months.

'Mariah has started the divorce process,' a source subsequently told E! News. 'She's getting all her ducks in a row."

Mariah tied the knot with Nick in 2008. They share three-year-old twins Moroccan and Monroe.