Katy Perry swipes at Madonna

Katy Perry has taken a swipe at Madonna for the amount of religious references which she sprinkles through her music and videos.

The Firework star's none too happy with artists who takes spirituality "lightly".

Katy herself is a dedicated Christian and the daughter of two pastors. She says, "For me, spirituality is something very important and I don't like it when people take it lightly.

"At times, I don't understand why there are artists who play that card, like when Madonna gets up on a cross to sing" (during her 2006 Confessions tour).

Katy's religious background has also forced husband Russell Brand to clean up his stand-up act.

She added, "Russell has made very blasphemous jokes in the past, but he's making fewer all the time because he knows that I am very sensitive about this subject."