But a spokesman for the Church said her claims were "false" and denounced "efforts to exploit Mr Miscavige's name."
"The Church has long respected the family unit while accommodating and helping those raising children," Karin Pouw, spokeswoman for the Church of Scientology International, told AFP.
"The Church does not engage in any activities that mistreat, neglect or force children to engage in manual labor. The Church follows all laws with respect to children," she said, accusing Miscavige-Hill of "apostate behavior."
In the book, published in February, the 29-year-old tells of hard labour she and other children were forced to do in the 1990s in the Ranch, in a remote part of the California desert.