BRITNEY Spears fans have been left stunned after a rough cut of her smash hit Toxic was leaked online.

The 35-year-old first released the track in 2004, but a raw vocal minus any auto-tuning used by producers has been making its way around the Internet.

While Britney has regularly been criticised for miming during her performances, the star proves she can definitely sing on the rough cut of Toxic.

However, her efforts still seemed to surprise even the most die-hard of her fans, with many taking to Twitter to discuss her impressive vocals.

One wrote: “Have you heard Britney Spears’ ‘toxic’ without autotune? It’s surprisingly good. Charooooot!!!” while another added: “Britney’s Toxic unedited version is just amazing!! Gosh I’m addicted!”.

A third wrote: “Is it only me who thinks that the #Britney singing Toxic without AutoTune is not that bad. Better than u could do!”

But it wasn’t just that fan, as another commented: “Britney Spears unedited Toxic is way better than the edited version. Loving the unedited version. #Leaked”.

Another follower hit back at critics who have taken swipes at Britney’s vocal abilities over the years, writing: “‘Toxic’ without autotune is a masterpiece. To those ladies who questioned about Britney’s talent”.

Toxic was taken from the star’s fourth album, In the Zone, and led to the star winning a Grammy Award in 2005 for Best Dance Recording.

The video to accompany the song has also become one of Britney’s classics, with the singer writhing around in a flesh coloured diamante covered body suit as well as being dressed as a sexy flight attendant.

The star is currently on tour in Japan, and showed off her abs as she took part in a grueling workout regime in preparation for her highly choreographed routines.

(Via The Sun)