Cardinal Robert Sarah has said that claims Pope Emeritus Benedict XVI did not co-author with him a new book on priestly celibacy are “defamations of exceptional gravity.”

The publisher of the book told CNA that critics suggesting that the pope emeritus did not co-author the book, or authorize its publication, are wrong.

“Are these people really implying that Cardinal Sarah is involved in a conspiracy to distort the truth?” Father Joseph Fessio, SJ, editor-in-chief of Ignatius Press, asked.

“If Cardinal Sarah is telling that the chapters from Pope Benedict are from Pope Benedict, we take his word for it,” Fessio said, adding that the publisher stands by its attribution of the book to both Sarah and Benedict.