Justin Bieber to duet with Mariah Carey on festive song

Justin Bieber is to record a Christmas song with Mariah Carey.

The 17-year-old revealed to fans on Twitter that he would be collaborating with the Grammy-winning singer on his festive album, Under the Mistletoe.

In a video message posted by Justin Bieber, Mariah Carey said the pair would be recording a duet of her song, All I Want For Christmas Is You.

"A lot of you are already surprised and you're going to be even more surprised when you hear it," said Mariah Carey.

The 41-year-old singer is the latest artist to collaborate with Justin Bieber on his Under The Mistletoe album.

They include the teenager's mentor Usher, R&B group Boyz II Men and rapper Busta Rhymes.

The first single from Bieber's Christmas album, Mistletoe, will be released on 18 October with the full album due for release on 1 November.