A report which documents the United States government’s Nazi-hunting operation has concluded that intelligence officials created a “safe haven” in the United States for Nazis and their collaborators after World War II.

The New York Times reported this past weekend about the 600-page report, which was written four years ago but which the U.S. Justice Department has tried to keep under wraps. The report, which catalogs the work of lawyers, historians and investigators at the Justice Department’s Office of Special Investigations (O.S.I.), which was created in 1979 to deport Nazis, provides new evidence about more than two dozen of some of the most notorious Nazi cases of the last three decades.

Talking about “the government’s collaboration with persecutors,” the report goes into detail about previous acknowledgements made by scholars and previous government reports that the C.I.A. used Nazis for postwar intelligence purposes. According to the report, O.S.I investigators learned that some of the Nazis “were indeed knowingly granted entry” to the United States, despite the fact that government officials were aware of their pasts. It concludes that the number of Nazis who entered the United States was almost certainly much smaller than 10,000, a figure which is widely cited by government officials.

Among the Nazis who were aided by American intelligence officials and whom the report discusses is Otto Von Bolschwing, an associate of Adolf Eichmann who had helped develop the initial Nazi plans to eliminate German Jews.  Von Bolschwing later worked for the C.I.A. in the United States. The C.I.A. was aware of his Nazi past, as is evident in a chain of memos in which they discuss what to do if he were confronted about his past.

Another case mentioned in the report is the case of Arthur L. Rudolph, a Nazi scientist who ran the Mittelwerk munitions factory. Rudolph was brought to the United States in 1945 as part of an American program that recruited scientists who had worked in Nazi Germany.  A 1949 memo written bythe Justice Department’s No. 2 official and cited in the report urges immigration officers to let Rudolph back in the country after a stay in Mexico. The official says that failure to allow Rudolph re-entry “would be to the detriment of the national interest.”

The Justice Department has resisted making the report public since 2006, but under threat of a lawsuit recently agreed to turn it over to a private research group, the National Security Archive. However, the version that was handed over had many sections missing, including a chapter on the case against John Demjanjuk. The chapter is missing part of a 1993 ruling by the United States Court of Appeals for the Sixth Circuit that raised ethics accusations against Justice Department officials.

Also omitted are references to Dr. Mengele, including how a director at the O.S.I. kept a piece of scalp that was thought to belong to Mengele in his desk, in hopes that it would help establish whether he was dead. The chapter describes the efforts by the O.S.I. to determine whether Mengele had fled to the United States and might still be alive.

Documents that have long been available to the public are also omitted. These include court decisions, Congressional testimony and front-page newspaper articles from the 1970s. The version reported on in the New York Times, however, is a complete version obtained by the newspaper.

The Times quotes the Justice Department as saying that the report was never formally completed and did not represent its official findings. The Departments added that the report included “numerous factual errors and omissions,” but would not say what they were.