NEW YORK • Zip it, Britney Spears is telling detractors who claim that she lip-syncs at her concerts.

Answering questions on an Israeli TV show ahead of her concert in Tel Aviv on Monday, the Toxic singer, 35, said she finds the rumours "really funny".

"A lot of people think that I don't do live. Because I'm dancing so much - I do have a little bit of playback, but there's a mixture of my voice and the playback.

"It really p***es me off because I am busting my a** out there and singing at the same time and nobody ever really gives me credit for it," said the singer, who is performing in Singapore tomorrow.

According to E! Online, her manager had also batted away the rumours about her performing style when he said in 2014: "To put on the show that she puts on, it's virtually impossible to sing the entire time and do what she does.

"She's singing on every song, basically, when she has the ability to sing. There's no way you can dance for 90 minutes straight and sing the entire time."

The nit-picking has not made her less of a draw in Las Vegas, where her residency show has reportedly almost sold out every show since she launched it in 2013, with more than 200 performances logged since.

There is another thing that Spears will not do on stage.

In an interview with an Israeli newspaper, she spoke about her performance at the 2001 MTV Video Music Awards, where she sang with a giant snake draped around her neck.

"That was pretty scary. Stupid even. I wouldn't do that again," said Spears, who will be making another stab at the perfume market with the launch of a new fragrance next month.