The card index, which contains about 47 million documents containing the names of most concentration camp inmates, forced-labour victims and refugees left homeless after World War II, had been the subject of an intense debate. Jewish groups had been pressing for open access to the collection, a storehouse of captured documents that began being assembled in 1946.

"Most of the documents were drawn up by the Nazis themselves," said Reto Meister, the Swiss Red Cross official now in charge of the files. "We have documents here about a horrifyingly wide range of victims: Jews and Christians, Eastern and Western Europeans, Germans and non-Germans, men and women. There's not one country where victims did not come from."

Opening the archive

The archive contains index cards on Nazi victims.

Previously, viewing the archive was limited only to survivors and close relations of the dead. All of that changed last year, when the members of the 11-nation governing commission of the International Tracing Service of the International Committee of the Red Cross agreed to provide greater access to the archives, ending a five-decade long debate over the victims' rights to privacy.

Earlier this year, the archive opened to historians. Wednesday's opening allows nearly anyone to search inside the archives, an especially important event for those friends and family members still searching for those unaccounted for after the war.

Meister also sees the files as the most potent answer to Holocaust deniers: "Anyone who wants to minimize the Holocaust should come here. We'll show him documents by the million."

The "overwhelming scale" of the card index, Meister said, was more persuasive than any debate.

Creating a digital archive in three capitals

Yad Vashem in Jerusalem has received digital archives.

The ITS has also made digital copies of much of the archives and exported them to Yad Vashem Memorial in Jerusalem, the US Holocaust Memorial Museum in Washington and the National Institute of Remembrance in Warsaw. The images include both sides of 9 million incarceration documents, 21 million cards from its main name index and 3.5 million papers in its displaced persons index.

Another block of documents relating to forced labour will follow in the summer, bringing scanning to 70 percent of the paper documents. The entire archival holdings are expected to be digitized by 2011 so that it can be mirrored in all three capitals.