One Direction producer Julian Bunetta says the band's choice in charity single was "very unexpected".

The British heartthrobs - comprising Harry Styles, Zayn Malik, Louis Tomlinson, Niall Horan and Liam Payne - have released a version of Blondie's 'One Way or Another' to raise funds for Comic Relief.

Producer Bunetta worked with the five-piece on the record and explained how the song came about.

He told MTV News: "It was Simon Cowell that came up with the idea and because obviously it's a really cheeky song and it's very fun and also it was very unexpected.

He added: "And I think that he wanted to do something that was out of the ordinary that people wouldn't expect. And, it obviously is fun and that works with the whole Comic Relief thing and the whole Comic Relief idea."

Bunetta - who worked with the five piece on 'Take Me Home' - says the singers were great to work with as ever.

He explained: "We had a lot of fun and then I came back to L.A. with all the vocal files and then spent a good amount of time trying to re-imagine it and how it could work and how I could make the sound fit

He continued: "It took a little bit of time, but I'm really pleased with the results, and I hope the 1D fans are really pleased with the results. They gave the song a new twist and a new life so I had to make sure I built it from there and accentuated and magnified what they brought to it. I built a box around them."