Three days before Japan attacked Pearl Harbor, British intelligence intercepted a "Most Secret" message from Japan that in retrospect seems to hint at imminent hostilities.
The message was among a few dozen documents released Thursday, the first of Winston Churchill's wartime intelligence files from 1941 and 1942 to become public. The rest of the 1,273 files went on view Friday.
Public records officials said the files leave open the question of whether Churchill knew Japan was going to attack the main U.S. base in Hawaii.
Two authors this year revived speculation that Britain's World War II leader knew the attack was coming and kept quiet in order to pitch America into the war.
The secret files of British intelligence are being opened under Prime Minister John Major's policy of lessening official secrecy. Historians hope they will shed new light on the war.
One document showed that Churchill knew of mass deaths in Nazi concentration camps in 1942. Jewish groups have long claimed that Britain knew more than it said about the death camps operated by the Nazis during the war.
None of the documents referred directly to Japan's carrier-borne aircraft attack on Pearl Harbor in the early hours of Dec. 7, 1941. About 2,400 Americans died in the attack. Nineteen ships and 120 aircraft were lost.
But one may have hinted at a step toward war. The message, dated Dec. 4, 1941, and marked "Most Secret," was an order from the Japanese foreign minister to the ambassador in Washington to burn secret documents and codes.
"None of the intercepts obviously indicate that British sources were aware in advance of the Japanese attack on Pearl Harbor, although it was clear that Japan was about to enter the war," the Public Records Office said.
But it added, "Historians making a detailed examination of all the relevant material might draw a different conclusion."
In a recent book, Betrayal at Pearl Harbor, authors James Rusbridger and Eric Nave claimed that Britain had cracked vital Japanese codes and was able to intercept naval signals that alerted them to an imminent attack on Pearl Harbor.
That hypothesis contradicts Churchill's account of how he had learned of the Japanese attack. In the third volume of his war memoirs, The Second World War, Churchill writes that he was having dinner on Dec. 7 at his country home in Chequers with John Winant, the American ambassador, and Averell Harriman, President Roosevelt's special envoy, when they turned on the news and heard "some few sentences" regarding "an attack by the Japanese on American shipping at Hawaii." They sat up surprised and his butler rushed in to confirm that he had also heard the broadcast, he wrote.
Churchill called Roosevelt, who he said replied: "It's quite true. They have attacked us at Pearl Harbor. We are all in the same boat now."
The prime minister writes of sending messages around the world and of what he felt at the time: "No American will think it wrong of me if I proclaim that to have the United States at our side was to me the greatest joy."
The report on German police activity dated Sept. 26, 1942, included a breakdown of deaths in the Nazi camps for August.
"Report on deaths in German prison camps during August reveal the following figures," the report stated.
"Niederhagen 21; Auschwitz 6,829 men, 1,525 women; Flossenburg 88; Buchenwald 74."
The report referred to a request for 1,000 Auschwitz prisoners for railroad work and said they couldn't be sent because of a "ban" _ apparently a quarantine _ on the camp.
"It appears that although typhus is still rife at Auschwitz, new arrivals continue to come in," added the report, which Churchill read.
Another report home from the Japanese ambassador to Berlin, dated Nov. 29, 1941, quoted Hitler's foreign minister, Joachim von Ribbentrop, as saying Hitler believed Britain could be defeated without invading.
"The Fuehrer believed that conditions in Britain were bad and thought that as a result of Germany's future operations, it might be, without an invasion, Britain would be beaten," the report said.
It added that the situation in Britain was "not too good," the Conservative Party was split and there was a "lack of confidence in Churchill."