However the demand for open access increased in 2009 after Pius was declared "venerable", the second of four stages on the way to sainthood, and this week Rabbi David Rosen, the worldwide director of interreligious affairs at the American Jewish Committee, welcomed the long-awaited move by the Vatican.
Once elected, Skorka urged the pontiff to use his influence to push for openness, a battle they finally won this week, as Francis revealed the secret archives would open on 2 March next year.
Francis said he made the decision understanding that serious historical research will evaluate "in a fair light, with appropriate criticism the moments of exaltation of this pope and, no doubt also moments of serious difficulties, tormenting decisions, and Christian and humane care".
The move could speed up Pius' path to possible sainthood, a complex process that in Pius' case bore the weight of questions of what he knew and did about Nazi Germany's systematic killing of Europe's Jews.
"For more than 30 years, the [American Jewish Committee] has called for the full opening of the Holy See's Secret Archives from the period of World War II", said AJC inter-religious affairs director Rabbi David Rosen.
Pope Francis appears to support Pius's actions, saying the late pope was criticized "with some prejudice and exaggeration".
The role of Pius XII, a staunch anti-communist who became pope in March 1939, six months before war engulfed Europe, has always been questioned by historians.
ASSOCIATED PRESS Pius XII on an inspection tour of Rome after an American air raid, October 15, 1943.
The Catholic Church has said Pius, who was pope from 1939 until his death in 1958, worked quietly to save Jews during the Holocaust, while remaining tight-lipped to protect Catholics in Nazi-occupied countries.
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He is expected to speak on Wednesday before the House of Commons Justice Committee, which is looking into the matter. Today Wilson-Raybould returned the support. "It doesn't help anyone to be in denial", she said then.
Vatican archivists had already started preparing the documents for consultation back in 2006, at the request of Benedict XVI.
"The church is not afraid of history", Francis told archive personnel during the announcement.
In Jerusalem, the Yad Vashem Holocaust memorial commended the decision and expressed the expectation that "researchers will be granted full access to all the documents stored in the archives".
Israel's foreign ministry, meanwhile, said it hopes there will be "free access to all relevant archives".
He noted in a statement that he had raised the issue with Francis and his predecessors in meetings.
"It is particularly important that experts from the leading Holocaust memorial institutes in Israel and the USA objectively evaluate as best as possible the historical record of that most bad of times, to acknowledge both the failures as well as the valiant efforts made during the period of the Shoah", Rosen told Reuters in an email, using the Hebrew word for the Holocaust.
Monsignor Sergio Pagano, in charge of the Vatican Secret Archive referred in comments Monday to the thousands and thousands of files, letters and other material to be made available.
Reflecting on the reign of "the Servant of God Pius XII, of venerable memory", Pope Francis said that he "guided the Barque of Peter in one of the saddest and darkest moments of the twentieth century".
The Vatican was officially neutral during the war.