The Vatican today sharply criticised a book on sexuality written by a prominent American nun, saying it contradicted church teaching on issues like masturbation, homosexuality and marriage and that its author had a "defective understanding" of Catholic theology.

The Vatican's orthodoxy office said the book, "Just Love: A Framework for Christian Sexual Ethics" by Sister Margaret Farley, a member of the Sisters of Mercy religious order and emeritus professor of Christian ethics at Yale Divinity School, posed "grave harm" to the faithful.