Madonna's brother Christopher Ciccone has revealed that his sister's marriage with Guy Ritchie is only tentatively held together by their matching religious convictions.

In Ciccone's book 'Life With My Sister Madonna', he claims that his relationship with his sister disintegrated after she met the 'Lock Stock' director and she committed to the Kabbalah faith.

He says: "The press may report that Guy isn't as involved in Kabbalah as Madonna, but that isn't true.

"Guy's world and his conversation nowadays revolve around Kabbalah. If the conversation strays to another topic they lose interest."

The singer's estranged sibling also alleges that Madonna is a stingy control freak, and insists that he was offended by the fact that his sister refused to help him with the expenses involved in attending her five-day wedding celebration in Scotland.

In addition to her lack of financial assistance, Chris claims that he had to endure the homophobic taunts of Guy's male friends throughout the lavish nuptials, and was shocked when the '4 Minutes' star didn?t come to his defence.

He writes: "I glance at my sister hoping to see a look of outrage on her face, but there is none.

"I am sad that Madonna, whose early success was built on her legions of gay fans, can listen to these comments without protest."

'Life With My Sister Madonna' is due for release tomorrow.