Britney Spears has hired a vocal coach ahead of her "top secret" announcement.

The "Ooh La La" singer has been teasing fans by adding a countdown to her website for a mysterious revelation that will be shared in 15 days time, but just two weeks before she announces her news, the blonde beauty has been having regular sessions with her voice instructor and working with a choreographer.

"Britney has been using a vocal coach and going to regular sessions and has also been working hard with her choreographer in preparation for what's coming up! With album eight on its way and a rumored Las Vegas residency in the pipeline, eagle-eyed fans have spotted that all of Britney's social networks have adopted a blacked-out theme... the mystery continues!" Britney's publicists said.

Meanwhile, Charli XCX - who co-wrote and featured on Icona Pop's number one hit "I Love It" earlier this year - previously said she has written a song for Britney's new album. "I've been doing some writing for the Britney record. I was freaking out. I didn't even want to go to the session I was so excited. I was so worried I would f**k it up. I was doing some stuff for that yesterday actually. Who knows how it will go. We've written one song and it's a great track and if she likes it then amazing. It was just an honour to be asked," she said previously.

Charli XCX is just one of the British stars Britney is looking to collaborate with on her new record - which is a follow-up to 2011's Femme Fatale - as she has also enlisted Naughty Boy to produce new tracks. The "La La La" hitmaker, who is best known for his work with Emeli Sande and Tinie Tempah, recently revealed that he and Britney's long-time producer William Orbit are behind her comeback single, which will be released soon.