Cardinal Elio Sgreccia, the Vatican's longtime top official on bioethics and sexuality, elaborated on the pontiff's comments, stressing that it was imperative to "make certain that this is the only way to save a life." Sgreccia told the Italian news agency ANSA that that is why the pope on the condom issue "dealt with it in the realm of ecceptionality."

The condom question was one that "needed an answer for a long time," Sgreccia was quoted as saying. "If Benedict XVI raised the question of exceptions, this expection must be accepted ... and it must be verified that this is the only way to save life. This must be demonstrated," Sgreccia said.

Christian Weisner, of the pro-reform group We Are Church in the pope's native Germany, said the pope's comments were "surprising, and if that's the case one can be happy about the pope's ability to learn."

William Portier, a Catholic theologian at the University of Dayton, a Marianist school in Ohio, said he had not read the report in the Vatican newspaper, but he said it would be wrong to conclude that the comments mean the pope has made a fundamental, broad change in church teaching on artificial contraception.

"He's not going to do that in an offhand remark to a journalist in an interview," Portier said.

In other comments, Benedict said:

• If a pope is no longer physically, psychologically or spiritually capable of doing his job, then he has the "right, and under some circumstances, also an obligation to resign."

• On Islam, in Europe, he declined to endorse such moves as France's banning the burqa or Switzerland's citizen referendum to forbid topping mosques with minarets.

"Christians are tolerant, and in that respect they also allow others to have their self-image," Benedict replied when asked if Christians should be "glad" about such initiatives. "As for the burqa, I can see no reason for a general ban."

• He was surprised by the scale of clerical sex abuse in his native Germany and acknowledged that the Vatican could have better communicated its response. "One can always wonder whether the pope should not speak more often."

• On Pope Pius XII, the wartime pontiff accused by some Jewish groups of staying publicly silent on the Holocaust: Some historians have asked the Vatican to put Pius' sainthood process on hold until the Holy See opens up its archives from his papacy. But Benedict said an internal "inspection" of those unpublished documents failed to support "negative" allegations against Pius.

"It is perfectly clear that as soon as he protested publicly, the Germans would have ceased to respect" Vatican extraterritoriality of convents and monasteries who were sheltering Jews from the Nazi occupiers in Rome. "The thousands who had found a safe haven ... would have been surely deported," Benedict argued.

In the book, Benedict also offers insights into his private life, saying he enjoys watching TV at home in the evenings with his secretaries and the four women who take care of his apartment, preferring the evening news and an Italian TV show from decades ago "Don Camillo and Peppone" about a parish priest and his bumbling assistant.

He said he always wears his white cassock, never a sweater, and wears an old Junghans watch that was left to him by his sister when she died. When he prays, he said, he prays to the Lord as well as the saints and considers himself good friends with Sts. Augustine, Bonaventure and Thomas Aquinas.