Part of the document cache - which includes World War II-era deportation lists, emigration documents, letters and photos found in Vienna in 2000 - will be included in an exhibition that opens in the Austrian capital next month.
The Holocaust Survivors Foundation USA issued a statement demanding to know why the materials apparently were not brought to the attention of groups trying to win compensation for Holocaust victims and their relatives.
"We do not understand how this valuable and pertinent documentation on Austrian Jewry was ignored," the Miami-based U.S. foundation said, adding that the find might have changed the outcome of settlements with insurance companies reached earlier this year.
"Each brittle page tells a story about real lives, real losses. ... We also recognize these documents as a crucial resource in current efforts to secure justice for survivors and heirs," it said.
"Life insurance policies looted by the Nazis that remain unpaid to their original owners are estimated to be valued in the billions of dollars. Yet the recently concluded claims process administered by the International Commission on Holocaust-Era Insurance Claims resulted in just 3 percent of these policies being settled or compensated."
Digital images of some of the discovered documents were to be screened at a panel discussion Thursday at the U.S. Holocaust Memorial Museum in Washington.
"The institutions responsible for bringing these archives to light also have an obligation to support survivors," the survivors' foundation said. "We do not understand how the major institutions working on processing and digitizing these Austrian materials ... failed to bring their contents to the attention of the public in a timely fashion so that a greater number of insurance cases might be settled."
Neither the Washington museum nor the Vienna-based Holocaust Victims' Information and Support Center immediately returned phone messages left by The Associated Press on Thursday, a national holiday in Austria.
Since 2002, Vienna's Jewish community and the Holocaust Memorial Museum have been working together to preserve the material on microfilm for a wider collection to include about 1.5 million documents from Vienna currently stored at the Central Archives for the History of the Jewish People in Jerusalem.
The latest documents were uncovered in 2000, when Jewish community members preparing to turn an apartment over to new owners stumbled upon about 800 dusty boxes and dozens of wooden cabinets packed with about half a million documents detailing the life of Viennese Jews during Nazi times.
In February, a federal judge in New York approved a settlement involving Holocaust victims, their relatives and Italian insurance company Assicurazioni Generali, ending a decade-long legal battle by families seeking restitution.
Under the deal, Generali - which already had paid US$135 million to settle previous claims - agreed to accept new claims until March 31. However, lawyers involved in the fight for compensation have been arguing for an extension, contending any new insurance records could bolster some claimants' cases.