Rita Ora says it was an ''indescribable honour'' performing for the Obamas.

The 24-year-old star took to the stage at the 33rd annual Christmas in Washington concert on Sunday (14.12.14) at the National Building Museum to sing Band Aid song 'Do They Know It's Christmas?' in front of US President Barack Obama, his wife Michelle, and daughters, Malia, 16, and Sasha, 13.

Following the event, Rita took to her Instagram account to post several pictures including one taken from Michelle's social networking site which sees her on-stage alongside the Obama family.

She captioned the message: ''Indescribable honour @michelleobama (sic)''

The blonde beauty also posted a picture of herself in a stunning black Dita Von Teese-inspired Ralph and Russo Couture dress ahead of her performance and admitted she was feeling very nervous.

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 (sic)''

Rita was joined by the Washington Youth Choir for the rendition of 'Do They Know It's Christmas?' and she later thanked Ralph and Russo Couture for dressing her and Bob Geldof for allowing her to play the Band Aid tune.

She wrote on Instagram: ''@ralphandrusso thank you for helping me create this moment. And Bob Geldof for letting me perform do they know it's Christmas to spread the word over seas in front of such influential people. We can make a difference together (sic)''

But Rita wasn't the only star to shine on the night as DWAYNE 'THE ROCK' JOHNSON also took to the stage to perform Christmas song 'Deck the Halls' - a nod to his former wrestling career - and Christina Perri sang 'Have Yourself a Merry Little Christmas'.

Earth, Wind and Fire, Aloe Blacc, Hunter Hayes and Darius Rucker also sang at the spectacle, and all of the performers got together at the end of the concert - a benefit event for paediatric care provider the Children's National Health System - to sing 'O Come, All Ye Faithful' and 'The First Noel'.