A choir of doctors and nurses beat Justin Bieber to the Christmas number one spot in Britain's pop music chart Friday after the heartthrob urged his fans to buy their song.

The Lewisham and Greenwich NHS Choir's charity single, "A Bridge Over You", outsold Bieber's "Love Yourself" to snatch the coveted festive top spot.

That came after Bieber wrote on Twitter Wednesday: "So for 1 week it's ok not to be #1. Let's do the right thing & help them win. It's Christmas. @Choir_NHS good luck".

The southeast London-based choir is made up of staff who work for the state-funded National Health Service.

Their song is a mash-up of "Bridge Over Troubled Water" by Simon and Garfunkel and Coldplay's "Fix You".

Other songs in this week's top ten which it has beaten include two other hits by Bieber plus Adele's "Hello" and One Direction's "History".

Harriet Nerva, a junior doctor in the choir, decided to start a social media campaign to get the song to number one after a particularly tough day at work.

"A patient with cancer that I had been looking after for quite a number of weeks died," she told the Guardian newspaper.

"I was listening to the song and it dawned on me that a great way of translating how I was feeling and how proud I was to work for the NHS would be getting (the song) to number one".

Britain's NHS is the fifth largest employer in the world, providing health care which is largely free at the point of delivery.

It is widely respected, with pollsters YouGov rating it the institution which most people view positively, and Prime Minister David Cameron's attempts to reform the service are highly politically sensitive.