Lady Gaga apologised to her fans on Wednesday as she was forced to cancel her Enigma show because she was too ill with bronchitis and a sinus infection to perform.

The singer was due to continue her residency at Park MGM in Las Vegas on Wednesday night, but took to Instagram to explain she'd had to axe the gig as she battled the illnesses.

Sharing a picture of herself hooked up to an IV and with an oxygen tube in her mouth, Gaga wrote: "I'm so devastated I can't perform tonight for so many people who travelled to come see me. Feel very sick and sad I never want to let you down.

"I'm just (too) weak and ill (to) perform tonight. I love you little monsters I'll make it up to you. I promise."

Despite her apology, Gaga's cancellation didn't go down too well with many of her fans - especially as it reportedly came just 20 minutes before she had been due to take to the stage.

"Flew 7000 miles to see @ladygaga in Vegas and she cancels 20 minutes before the show... I love you Gaga, but I am f**king devastated #GagaVegas #Enigma," fan Alex Rose tweeted after flying to Vegas from the U.K. to watch the show.

Alex told the Mirror Online that she was "losing faith" in the singer as Wednesday's gig was the third Gaga concert she had tickets to that had been cancelled.

The 33-year-old is next due to perform on Friday night, but it's as yet unclear whether or not she will be well enough for that show.