In the war of words over who was to blame for the surprise Japanese attack on Pearl Harbor 41 years ago, fresh evidence is emerging that the late FBI director J. Edgar Hoover had a hand in the intelligence bungles that led the United States to heed none of the warnings that the invasion was imminent.

The new evidence is supplied by Michigan State University historians John F. Bratzel and Leslie B. Rout Jr., who write in the current issue of The American Historical Review that Hoover received a double warning more than three months before the attack that the Japanese were thinking of making a surprise aircraft attack on the American fleet in Pearl Harbor.

Based on information in 40-year-old FBI documents and documents from the FDR library near Hyde Park, N. Y., the two historians also claim that the double warning to Hoover is the "missing evidence" that Pulitzer Prize-winning author John Toland said he and other Pearl Harbor writers have sought for years. Toland claimed in his last book, "Infamy," that the "disappearance" of this evidence was part of a "cover up" to purge intelligence records damaging to high officials in the Franklin D. Roosevelt administration.

Bratzel and Rout write that the story of the "missing evidence" begins in 1939 in Yugoslavia, where German military intelligence recruited a Mediterranean playboy named Dusko Popov to spy in England for them. Popov (code name Ivan) agreed but turned double agent (code name Tricycle) as soon as he arrived in England. The German Abwehr (intelligence) soon trusted Popov so much that they told him to go to the United States to set up a spy ring, an instruction that Popov immediately communicated to British intelligence.

Upon his arrival in New York, Popov was met by agents of the FBI who grilled him for days. In his memoirs, Popov said that one of his first statements to FBI bureau chief John Foxworth was: "You can expect an attack on Pearl Harbor before the end of the year . . . "

The Michigan State historians say Popov had two pieces of evidence to back up his warning. One was a verbal communique' from the German air attache' in Tokyo, who had escorted Japanese naval officers to the Gulf of Taranto below the Italian boot, where British warplanes from the aircraft carrier HMS Illustrious had devastated the Italian fleet in November of 1940.

"The Japanese wanted to know all about the attack in infinite detail," the historians write. Popov's German sources "had concluded that the Asian member of the Tripartite Alliance was planning to duplicate the British feat."

Of far more importance, the historians write, was the telegram in Popov's possession when he arrived in New York. Hidden on the face of the telegram was a microdot message to Popov asking for defense information about the U.S. and Canadian air forces and listing a series of questions the Japanese had asked their German allies to answer. One third of the questions pertained to the defense installations that ringed the U.S. naval base at Pearl Harbor.

"The Germans wanted sketches showing the exact locations of Hickam, Wheeler and Kaneohe airfields," the historians write. "They likewise wanted sketches of the installations at Pearl Harbor and detailed information concerning dredging, depth of water, torpedo nets, anchorages and the like."

The historians write that Popov was passed on to J. Edgar Hoover, who chastised him for taking his unmarried girlfriend to Miami and then took only a small portion of the microdot material on the telegram to translate and pass on to the White House, the military intelligence division and the Office of Naval Intelligence. The historians claim that none of the questions the Germans asked about Pearl Harbor were passed by Hoover to the White House or anybody else.

"Hoover used the information to demonstrate how efficient the FBI was (about discovering the microdot system) rather than to warn of a possible attack," the historians write. "The full text of Popov's questionnaire still rests in the files of the FBI, where it has been for over 40 years."

Why did Hoover not send the full text of the microdot questionnaire to the White House? "Hoover wanted to look good to the president and gain points against his rivals -- namely, the other U.S. intelligence agencies and MI6 (British intelligence)," the historians conclude. "Clearly, he also found Popov and his style of living abhorrent and did not trust him."