BERLIN -- Nazi Germany tested a crude nuclear device in March 1945, killing hundreds of people in a massive explosion in southeastern Germany, a German researcher claims in a new book published yesterday.
That the Nazis conducted nuclear experiments has been known for decades, but ''Hitler's Bomb," by Berlin academic Rainer Karlsch, suggests they may have been closer to building an atomic weapon for military use than previously believed.
No independent corroboration of the claims was immediately available.
''Hitler's bomb -- a tactical nuclear weapon with a potential for destruction far below that of the two American atomic bombs -- was tested successfully several times shortly before the end of the war," Karlsch said in the book.
What Nazi Germany lacked was enough fissile material, such as enriched uranium, to make a full-size, functioning nuclear bomb, he said.
Other researchers already have theorized that the Nazis conducted crude nuclear experiments, but Karlsch said he has discovered additional evidence, notably in the archives of the former Soviet Union. The book cites postwar witness accounts and Soviet military intelligence reports to back up its theory of a March 3, 1945, experimental nuclear test blast at the Nazis' Ohrdruf military testing area -- then run as a concentration camp by the Nazi SS -- but offers no firsthand documentary evidence.
Russia's nuclear agency said it was unaware of any such test.
''We do not have information that something of this kind happened," said Nikolai Shingaryov, a spokesman for Russia's Federal Nuclear Agency. ''Of course, we don't know everything."
In an interview published in Literaturnaya Gazeta in 2002, Russian academic Valentin Belokon described a letter from the presidential archive addressed to Soviet secret police chief Lavrenty Beria on March 30, 1945, that includes a description of the construction of a German atomic bomb intended for transportation on a V-2 rocket.
A US mission that arrived in Germany with American troops in 1945 to investigate the German atomic bomb program concluded that the Germans were nowhere near making a nuclear weapon.
Gerald Holton, a professor of physics and the history of science at Harvard University, said the main scientists in the Nazi atomic bomb program never mentioned a test blast or having built a working nuclear reactor. Allied intelligence eavesdropped on the scientists, including the effort's leader, Walther Gerlach, while they were interned at Farm Hall manor in England after the war.
Karlsch concludes that the blast killed several hundred prisoners of war and Nazi inmates forced to work at the site. Two months later, on May 8, 1945, Nazi Germany surrendered after the Soviets captured Berlin.
The German device probably was a 2-ton cylinder containing enriched uranium, Karlsch said. The amount of uranium was so small that the conventional explosives used to trigger the device did not set off a vastly more destructive nuclear chain reaction, he added.
That would mesh with a graphic account Karlsch said he found in Soviet military archives, apparently based on information from a German informant, that the blast felled trees within a radius of about 1,640 to 1,968 feet.
Karlsch, an economic historian, acknowledged he had no proof the Nazis conducted a nuclear test blast, but he hoped his book would provoke more research.