Britney Spears got her 20 million Twitter followers in a bit of a flap after posting a photo of herself in a bikini.

The X Factor USA judge took the photo as she enjoyed some sun rays before autumn and winter set in.

She tweeted: "Having some fun in the sun... don't want summer to be over!"

Collaborator will.i.am meanwhile tweeted the star in response - and it seems he liked what he saw. The Black Eyed Peas man said:

"@britneyspears OMG...your lookin fit & hot...can't wait to shoot the video to our song...your fans are ganna love it..."

Britney Spears meanwhile recently spoke out in praise of fellow X Factor judge Demi Lovato, who she said encourages her to be "stronger".