VATICAN CITY (Reuters) - The use of condoms to stop the spread of AIDS may be justified in certain cases, Pope Benedict says in a new book that could herald the start of sea change in the Vatican’s attitude to condoms.

In excerpts published in the Vatican newspaper on Saturday ahead of the book’s publication next week, the pope cites the example of the use of condoms by prostitutes as “a first step toward moralization” even though condoms are “not really the way to deal with the evil of HIV infection.”

While some Roman Catholic leaders have spoken in the past about the limited use of condoms in specific cases to stop the spread of HIV/AIDS as a lesser of two evils, this is the first time the pope has mentioned the possibility himself in public.

The Vatican newspaper unexpectedly published significant excerpts from the book on Saturday night, days before extracts were initially due to be made public.

The pope’s words appeared to be a major shift in the Vatican’s attitude. While no formal position existed in a Vatican document, the majority of Church leaders have been saying for decades that the use of condoms was not even part of the solution to fighting aids.

The late cardinal John O’Connor of New York famously branded the use of condoms to stop the spread of AIDS as “The Big Lie.”

Last year, the pope caused an international uproar when he told journalists taking him to Africa that condoms should not be used because they could worsen the spread of AIDS.

The new book, called Light of the World, is made up of Benedict’s responses to questions by German Catholic journalist Peter Seewald over a month of meetings at the papal summer residence.

The pope says that the “sheer fixation on the condom implies a canalization of sexuality” where sexuality is no longer an expression of love “but only a sort of drug that people administer to themselves.”

After the pope first mentions that the use of condoms could be justified in certain limited cases, such as by prostitutes, Seewald asks: “Are you saying, then, that the Catholic Church is actually not opposed in principle to the use of condoms?”

The pope answers: “She of course does not regard it as a real or moral solution, but, in this or that case, there can be nonetheless, in the intention of reducing the risk of infection, a first step in a movement toward a different way, a more humane way, of living sexuality.”