The Vatican’s incoming Secretary of State has said that priestly celibacy is not dogma and is open to discussion, suggesting a significant shift in approach to one of the oldest traditions in the Catholic Church.

"Celibacy is not an institution but look, it is also true that you can discuss (it) because as you say this is not a dogma, a dogma of the church," Archbishop Pietro Parolin said during a recent interview.

He added that while it is not dogma, celibacy is a deeply entrenched Catholic tradition.

Speaking to the Venezuelan newspaper El Universal he said, "The efforts that the church made to keep ecclesiastical celibacy, to impose ecclesiastical celibacy, have to be taken into consideration," Parolin said. "One cannot say simply that this belongs in the past."

The question, he said, represents “a great challenge for the pope.”

He added that “it is possible to discuss and reflect on these topics that are not defined faith, and consider some modifications, but always in the service of unity and according to God’s will.”

Parolin, 58, is the head of the Vatican government and seen as the most powerful official after the Pope.

Father Federico Lombardi, the director of the Holy See’s press office, said Parolin’s comments were "in line with the teachings of the church."

Parolin was the diplomatic representative of the Holy See in Venezuela. In August it was announced he will succeed Cardinal Tarcisio Bertone as the Holy See's secretary. He is completing his term as papal nuncio in Venezuela before assuming his new post in mid-October.

In an interview last year, former Cardinal Jorge Bergoglio, now Pope Francis, said the Catholic Church’s law on celibacy among priests “can change.”