WILMINGTON, Delaware (AP) - US authorities have recovered about 400 handwritten pages from the wartime diary of a key Nazi adviser to Adolf Hitler after a 17-year search for the documents, officials said on Thursday.

Alfred Rosenberg played a significant role in the slaughter of millions of Jews and other non-Aryans considered inferior under the Third Reich. He was convicted of war crimes at the Nuremberg trials after World War II and executed in 1946.

Officials from the Department of Homeland Security and the Justice Department joined officials from the US Holocaust Memorial Museum for a news conference on Thursday to outline how they found the documents, which cover the years 1936 to 1944.

"One of the enduring mysteries of the Second World War is what happened to the Rosenberg diary," said John Morton, director of US Immigrations and Custom Enforcement. "We have solved that mystery."

Gerhard Weinberg, professor emeritus of history at the University of North Carolina and a leading historian on the Nazi era, said the diary could shed new light on Rosenberg's role in administering the occupied eastern territories, and his relationships with other high-ranking Nazi officials.

Museum officials wrote in a Web posting on Thursday that the documents provide valuable information, as Rosenberg helped orchestrate the looting of artwork and other valuables from Nazi-occupied territory during that the time.

"Its discovery will undoubtedly give scholars new insight into the politics of Nazi leaders and fulfills a museum commitment to uncover evidence from perpetrators of the Holocaust," the posting said.

Researchers have yet to begin a thorough examination of Rosenberg's diary. But Henry Mayer, a senior adviser on archives for the Holocaust museum, suggested that it will offer some "amazing new evidence" and that he believes some of the material will contradict written history.

Rosenberg, a Nazi ideologue and propagandist, was the author of The Myth of the Twentieth Century, a 1930 book espousing the superiority of Aryan culture over the Jewish race. He later led the Nazi Party's foreign affairs department and rose through the party hierarchy to become Reich Minister for the Occupied Eastern Territories in 1941.

"It's important that as soon as possible, somebody decipher the handwriting and publish, hopefully, an annotated edition of this material," Prof Weinberg said. "It is also possible that we will all be disappointed. There may turn out to be very little that we don't know."

Among early translated excerpts is a passage from 1941 in which Rosenberg wrote proudly of a conference marking "the first time in European history that 10 European nations were represented at an anti-Jewish conference with the clear programme to remove this race from Europe."

Later that year, Rosenberg wrote of reports that Russian leader Josef Stalin had ordered the 400,000 Volga Germans "to be dragged away to Siberia, i.e. to have them murdered".

Other translated excerpts involve the 1936 Olympic games, including Rosenberg's assertions that Britons were "angry about the negroes from the USA as they squeeze out the English during the Olympic Games".

Officials said his diary was smuggled into the United States after the war, most likely by Robert M.W. Kempner, a government lawyer during the Nuremberg trials.

Kempner died in 1993, and museum officials later took possession of some of his extensive document collection. But the Rosenberg diary remained missing until recently.

Mayer said the search for the diary dates to 1996, when two of Kempner's former legal secretaries approached a Holocaust museum official about Kempner's collection of papers.

Mr Mayer said officials later learned that the two secretaries and "another gentleman from upstate New York" had taken the missing papers. Officials later found the materials at a home in Lewiston, New York, with the help of a private investigator and former FBI agent.

Acting upon a warrant issued by a federal magistrate judge, authorities seized the diary in April. Authorities repeatedly refused to say who had the diary.