Britney Spears
Britney Spears is in the midst of a two-year residency in Las Vegas, performing 200 shows Ethan Miller/Getty

Pop star Britney Spears interrupted her latest Las Vegas concert to swear at a concert-goer who reportedly hurled an insult about her weight.

The 33-year-old was performing her 2011 track Till The World Ends at the Planet Hollywood Hotel & Casino when a member of the audience is said to have called her a "fat bitch".

In video footage shared on Instagram, Spears can be heard shouting into her microphone: "F*****g a*****e", before continuing a routine with her dancers.

The Scream & Shout singer has been open about her fitness regime and weight-loss goals in the past and recently explained how she got into shape after giving birth to her two sons, Jayden and James.

Spears told the December 2014 issue of Women's Health: "After I had Jayden, it was real easy for me to get back in shape. But five years later, I started noticing changes in my body. My hips are a little bit wider because I've had kids. So it was crucial for me to be continuous with my exercise."

Warning: Explicit language

The Hit Me Baby One More Time hitmaker also revealed that performing on stage is probably the biggest workout she does, adding: "Dancing is a great cardio workout. Tough and fun at the same time.

"I like my workouts to be effective in a short amount of time. I start with 20 minutes of intense cardio - usually running - move on to light free weights, bodyweight exercises such as push-ups, squats and sit-ups, then finish it off with a stretch."

Hopefully Spears will perform to more of a complimentary audience at the Billboard Music Awards on 17 May, when the singer will reportedly join rapper Iggy Azalea on stage for a surprise duet of their new single, Pretty Girls.