Katy Perry copied a track from a Christian rap song, a US court has found.

The court ruled that the beat and instrumental line from the singer's 2013 song 'Dark Horse' was taken from the 2009 track from Christian rap artist Flame. Perry denied that she had ever heard the song, 'Joyful Noise,' during the week long trial. Her defence team also claimed that the beats in both songs were "commonplace" and that Flame, whose real name is Marcus Tyrone Gray, could not claim copyright on the track. Sky News reports that the Los Angeles court ruled against Perry on Monday, confirming that the instrumental line and beat present in over half of 'Dark Horse' was copied from the Christian track. Gray's team had argued that Perry had started her career in Christian music and said that her team were "trying to shove Mr Gray into some gospel music alleyway that no one ever visits." Perry and the song's co-authors claimed that they did not listen to Christian music. During the trial, the singer offered to perform her song after a broken speaker system would not allow the track to be played inside the courtroom. Her request was denied. 'Dark Horse' was released on Perry's fourth album Prism in 2013. It secured a top spot on the Billboard Top 100 chart for four weeks, also earning the star a Grammy nomination. The court will now decide on damages for Gray from Perry.