Pop star Katy Perry is being sued by a group of Christian rappers including Flame and Lecrae amidst allegations that she ripped off their track for her hit song 'Dark Horse'.

'Joyful noise', written in 2007 and released on Flame's album 'Our World: Redeemed' a year later, features Christian artists Lecrae, Emanuel Lambert and Chike Ojukwu. It received a Gospel Music Association Dove Award nomination for the Best Rap/Hip Hop Recorded Song of the Year in 2008, while the album was nominated for a Grammy Award.

The two songs have a similar sound, and Flame, Lecrae et al contend that Perry's hit, released five years later, infringes copyright laws by reproducing material from 'Joyful noise' without consent.

"Specifically, defendants' unauthorized reproduction, distribution, and public performance of plaintiffs' musical composition constitute infringement of plaintiffs' exclusive rights in their copyright," the lawsuit, filed on Tuesday, states.

The claimants are also suing for damages – they insist that Perry's song, which remained No. 1 in the Billboard charts for weeks, has "irreparably tarnished" their Christian message through its use of satanic imagery. The 'Teenage Dream' singer faced criticism in January after her performance at the Grammy Awards featured a display of witchcraft and demons, and even portrayed Perry herself being burned at the stake as a witch.

The 29-year-old was once known as Gospel singer Katy Hudson, however, over recent years she has distanced herself from her Christian roots, telling Marie Claire magazine last year: "I'm not Buddhist, I'm not Hindu, I'm not Christian, but I still feel like I have a deep connection with God".

"The devoutly religious message of 'Joyful Noise' has been irreparably tarnished by its association with the witchcraft, paganism, black magic, and Illuminati imagery evoked by the same music in 'Dark Horse,'" the lawsuit continues.

"Indeed, the music video of 'Dark Horse' generated widespread accusations of blasphemy and an online petition signed by more than 60,000 demanding removal of an offensive religious image from the video."

Flame, real name Marcus Gray, allegedly filed the suit after seeing a blog post on SoundsJustLike.com which compares his track to Perry's.

He has repeatedly expressed a passion for sharing the Gospel through his music, declaring: "I just want to encourage the Christian and the non-Christian who may be interested in peeking over the fence of Christianity that in this faith, in this worldview, you've been set up to win".

Compare the two tracks for yourself below: