A secret report condemned the US government for knowingly allowing Nazis to settle in America after the World War II.

“America, which prided itself on being a safe haven for the persecuted, became in some small measure a safe haven for persecutors as well,” the 600-page document, chronicling the history of the US Justice Department’s Nazi-hunting unit, said.

The New York Times obtained a copy of the report, which the National Security Archive, a private group, posted on its website.

Earlier, the Justice Department had declared dozens of pages from the document off-limits to the public after the archive sued to get it.

The long-secret report provided new details of many of the major cases handled by the Office of Special Investigations.

The report reflects the ways in which American officials assigned to recruit foreign scientists after the war circumvented President Harry Truman’s order not to bring in Nazi Party members or people who had actively supported Nazi militarism.

Arthur Rudolph, one of hundreds of scientists brought to the US after the war, told investigators in 1947 of attending a hanging during the war of inmates accused of sabotage at a slave labour plant manufacturing V2 rockets near Nordhausen, Germany, where he was operations director.

US immigration officials knew Rudolph had been a Nazi party member, but he was admitted to the country anyway, and went on to become honoured in the US as the father of the Saturn V rocket, enabling the US to make its first manned moon landing.

Rudolph went to Germany in 1984 and forfeited his US citizenship.

The report also details a discussion at the CIA over whether former Nazi party member Otto Von Bolschwing should acknowledge his Nazi past if confronted about it when applying for US citizenship.

Reversing earlier CIA advice, the agency concluded that Mr Bolschwing should tell the truth. The agency hired Mr Bolschwing during the Cold War for his contacts among ethnic Germans and Romanians. The Justice Department sought to deport Mr Von Bolschwing when it found out about his past.

Mr Von Bolschwing, it turned out, had worked with Adolf Eichmann, one of the architects of the Holocaust, helping devise programmes in the 1930s to persecute and terrorise Germany’s Jews.

“Some may view the government’s collaboration with persecutors as a Faustian bargain,” the report states. “Others will see it as a reasonable moral compromise borne of necessity.”

In court filings in the lawsuit brought by the National Security Archive, the Justice Department said the report was never finalised, contained numerous factual errors and omissions and did not represent the department’s official position.