Singer Rita Ora performed on the stage at the 33rd annual Christmas in Washington concert and says it was an "indescribable honour".

The pop star sung to the Band Aid song "Do they know it's Christmas" before the US President Barack Obama, his wife Michelle and daughters -- Malia and Sasha at the Sunday concert.

Afterwards, Ora posted pictures on her Instagram account, which show her on stage beside the Obama family, reports femalefirst.co.uk.

She captioned the image: "Indescribable honour @michelleobama".

She wrote on Instagram: "Ok I can't help it little sneak peak of my face before walking on the Obama stage. My legs were like jelly!! Thank you Audrey Hepburn for the inspiration!!#breakfastattiffs".

Ora was accompanied by actor Dwayne Johnson, who sang "Deck the halls", and singer Christina Perri sang "Have yourself a merry little Christmas".