VATICAN CITY (CNS) -- New Vatican norms aim to bar from the priesthood men with "deep-seated" homosexual tendencies, not those who may have experienced and overcome transitory episodes, a Vatican official said.

Cardinal Zenon Grocholewski, head of the Congregation for Catholic Education, strongly defended the document in an interview with Vatican Radio Nov. 29, the day it was officially released at the Vatican. Vatican Radio posted the transcript of the interview.

Cardinal Grocholewski said the document's distinction between deep-seated and transitory homosexual tendencies was important.

"Obviously, if we speak of deep-seated tendencies, this means that on the other hand there can also be transitory tendencies or transitory cases that do not constitute an obstacle," he said. "For example, some curiosity during adolescence; or accidental circumstances in a state of drunkenness; or particular circumstances, like someone who was in prison for many years."

Or, in some situations, he said, homosexual acts may be a way to please someone in order to obtain favors.

"In such cases, these acts do not originate from a deep-seated tendency but are determined by other transitory circumstances, and they do not constitute an obstacle to admission to the seminary or to holy orders. However, in such cases, they must cease at least three years before diaconal ordination," he said.

Cardinal Grocholewski said the norms were designed to help discern future vocations and do not apply to already ordained homosexual priests.

"Clearly, these ordinations are valid, because we are not affirming they are invalid," he said.

He also said that someone who discovers his own homosexuality after priestly ordination should "fulfill his priesthood and seek to live in chastity."

"Perhaps he would need more spiritual help than others, but I think he should carry out his own priesthood in the best possible way," he said.

Cardinal Grocholewski said that in drawing up the norms, the education congregation was simply taking the church's teaching on homosexuality and applying it to seminaries and the priesthood. That is important today because of widespread confusion about homosexuality in modern society, he said.

"Many people defend the point of view that the homosexual condition is a normal condition of the human person," he said. But that idea goes against human anthropology and church teaching on natural law, he said.

The church teaches that homosexual acts are gravely sinful violations of natural law, he said.

"That is distinct from the homosexual inclination or deep-seated tendencies. And yet this tendency is considered, in the 'Catechism of the Catholic Church,' as an inclination that is objectively disordered," he said.

"Why? An inclination like that is certainly not a sin, but it is a tendency more or less strong toward a behavior that is intrinsically bad from a moral point of view," he said.

Those with a homosexual inclination find themselves facing a trial and deserve understanding, he said. They should not be discriminated against in any way, he said.

But their exclusion from the priesthood should not be seen as discrimination, he said. People should understand that the church has a sacred right to discern men suitable for priestly ordination.

"It is not discrimination, for example, if one does not admit a person who suffers from vertigo to a school for astronauts," he said.