Madonna is not impressed that Britney Spears has dropped Kabbalah as her religion.

Spears — who had embraced the religion in an attempt to clean up her act — has now given it the boot.

A source told The News Of The World: "Madonna is dismayed that Britney has just dropped Kabbalah.

"She always believed it is a way of life, not just something to pick up and get rid of on a whim."

Spears — who was due to perform a duet with Madge as part of the US leg of her 'Sticky and Sweet' tour — has subsequently been dropped from the line up.

The source said: "Madonna doesn't feel she can work with Britney anymore because they're just not aligned in a spiritual level."