Klaus Fuchs, the German-born spy convicted in 1950 by Great Britain of giving atomic bomb secrets to the Soviet Union, was identified as a communist agent in German documents captured and brought to the United States five years before his arrest.

The documents are lists of native German nationals suspected of being communists and of living in the Soviet Union. They were drawn up by a German SS agency in June, 1941, before the Nazis invaded the Soviet Union.

The lists were published by the Reich Central Security Office of the SS and distributed to SS units due to move into the Soviet Union behind German tank divisions.

Now in the National Archives, the documents are an example of warnings that went unheeded by U.S. intelligence in the case of Klaus Emil Julius Fuchs.

Fuchs witnessed the first explosion of an atomic bomb in the New Mexico desert in 1945 and worked on the atomic bomb project at Los Alamos National Laboratory after World War II. Now 70, he lives in East Germany near Dresden.

In the capured documents, his name appears as No. 210 on a list that includes thousands of suspected communists.

The documents indicate that the names were being passed from the Reich Central Security Office in Berlin to the Gestapo in the German city of Kiel just before the invasion of Russia. Next to Fuchs' name is the notation: "Bring him in if found in the Soviet Union."

There is no question that the Klaus Fuchs identified by the Nazis as a communist is the man who served nine years of a 14-year prison term in Britain before his release in 1959.

His birthdate is given as Dec. 29, 1911, and his birthplace as Ruesselsheim near Frankfurt, where the confessed atomic spy was born.

At the time the Gestapo was told to look for Fuchs in the Soviet Union in 1941, he had been interned by the British in Canada as a German alien. His whereabouts in the years 1933 through 1940 are unclear.

Fuchs returned to Great Britain in 1942, began work on atomic research at Birmingham University and became a naturalized British citizen.

A Canadian royal commission on espionage is believed to have suspected as early as 1946 that Fuchs was a communist spy when a Soviet embassy clerk in Ottawa, Igor Gouzenko, disclosed the existence of a Soviet spy ring in Canada to the Royal Canadian Mounted Police.

Fuchs' name was said to have been written by Col. Vassily M. Rogov, leader of the Soviet spy ring in Canada, into a notebook later found by Canadian counterespionage agents.

In his confession about passing nuclear secrets to the Soviets, Fuchs said:

"When I learned about the purpose of the work [he was to do on nuclear research], I decided to inform Russia and I established contact through another member of the Communist Party. Since that time, I have had continuous contact with persons completely unknown to me except that they would give information to the Russians."