Britney Spears stormed off stage during a show in Canada because of a marijuana-related "ventilation issue."

Fans were left stunned when the star halted her show in Vancouver after just three songs and left the stage without an explanation.

After forty minutes an announcement was made over loudspeaker, reportedly ordering the audience to stop smoking marijuana and cigarettes in the arena as it was "unsafe" for Britney to mime, sorry, perform.

When the show ended, Britney delivered an anti-drugs message to the crowd,  telling them, "Thanks Vancouver. You were wonderful. Drive safe. Don't smoke weed!"

A rep for the Womanizer star has since explained that the glitch was caused by poor air circulation.

And concert organisers at Orca Bay Sports and Entertainment denied marijuana smoke was to blame, insisting audience members were puffing cigarettes.

A statement from Britney's camp reads: "We want to apologise to all the fans who attended our Vancouver show tonight for the brief pause in Britney's set. Crew members above the stage became ill due to a ventilation issue."