Katy Perry has shot to the top of the UK iTunes chart after releasing her new song Roar ahead of its scheduled release date.

The song is the lead single from Perry’s upcoming album Prism and was released ahead of its original September 8th release date since it was already out in the majority of other countries.

Perry tweeted: “YAY UK! A week early & by popular demand you can be louder than a lion! Finally, It's your turn to ROAR! http://smarturl.it/PRISM  #RoarUK”

Roar has already reached the top of the Billboard charts in the US and has now knocked Ellie Goulding who was number one in the UK with her song Burn.

Perry has revealed that she is extremely excited ahead of the release of Prism and that it won’t contain any “darkness”.

She said: "I was saying that when I was going through a different phase, but I really let that light in.

"The reason why I called this record Prism is because I actually finally let the light in."

Prism will be released on October 22nd.