Britney Spears turns 36

Britney Spears celebrated turning 36 by serenading her Instagram followers with an Elvis Presley song.

The pop princess turned Las Vegas diva posted a video online showing her at home, in a skimpy black dress, singing Can't Help Falling In Love.

As she delivered the classic track the camera panned around her, showing off a foyer decorated with a huge Christmas tree and twinkling lights.

The singer, who celebrated her birthday on Saturday, said she had been inspired to give the performance by Madonna, who covered Spears' song Toxic online this week.

She wrote: "I was really inspired yesterday by @madonna's post. She's right... silence = death! These words really stuck with me, because they are so true.

"I've always wanted to do a performance like this... singing in a pretty little black dress, with a simple 360, one take shot!

"I figured since it was my birthday, why not go for it?!

"So boom When the clock struck 12:00, I did it!!!

"Thank you all for the beautiful birthday wishes, and for letting me do what I love. I appreciate you more than you will ever know!!!!"

Madonna covered Toxic online to mark World Aids Day on December 1.

She said on the site: "Silence = Death! Song For World AIDS Day! #toxic #poisonparadise @britneyspears. Happy Birthday!!"

Spears and Madonna famously locked lips on stage at the MTV Video Music Awards in 2003.