New Britney Spears song 'Strangest Love' leaks? Listen now
The song - called 'Strangest Love' - appeared on YouTube on Christmas Day (December 25) and has been featured on several of the singer's fansites.
Spears's 'Femme Fatale' tour DVD was certified platinum in the US by the Recording Industry Association of America (RIAA) earlier this week.
She completed the worldwide tour in Puerto Rico on December 10, the week after her 30th birthday.
Spears also recently became engaged to her boyfriend and former manager Jason Trawick, who features with her in the video to recent single 'Criminal'.
The couple celebrated the news in Las Vegas earlier this month as part of a joint event also marking Trawick's 40th birthday.
Watch Britney Spears and Jason Trawick in the video to 'Criminal' below: