LONDON (AP) _ Lord Shawcross, who was Britain's chief prosecutor at the Nazi war crimes trials in Nuremberg and a representative at the United Nations through the late 1940s, died Thursday, his secretary said. He was 101.

Hartley William Shawcross was involved in a number of high-profile cases throughout his career, prosecuting a major treason trial and an atomic spying case.

Shawcross died at his home in Cowbeech, south of London, said his secretary, Greta Kinder. The cause of death was not announced.

He was elected to Parliament when the Labor Party swept to power under Clement Attlee in 1945, ousting Winston Churchill's Conservative Party, and quickly became the new government's attorney general.

Shawcross then was appointed Britain's chief prosecutor at the Nuremberg, Germany, trials of Nazi war criminals, signing an indictment along with representatives of the United States, France and the Soviet Union.

Shawcross called the Nazi defendants ``black-hearted murderers, plunderers and conspirators of which the world has not known their equal.''

``There comes a point when a man must refuse to answer to his leader if he is also to answer to his own conscience,'' he said in court.

He later admitted to having some respect for Adolf Hitler's aide, Hermann Goering, who killed himself the night before he was to be executed.

``A criminal no doubt, but a courageous one, and a man of great ability and outstanding personality,'' Shawcross said. ``He defeated the gallows by taking poison in his cell, and for that I take my hat off to him.''

Shawcross served as one of Britain's representatives at the United Nations through the late 1940s.

As attorney general, he led one of the nation's most infamous treason cases, prosecuting William Joyce, known as ``Lord Haw-Haw,'' for aiding the Nazi propaganda effort during World War II.

Joyce, who was active in British fascist groups before the war, was a U.S. citizen who also held a British passport when he broadcast from Germany. Shawcross successfully argued that as long as Joyce possessed that document, he owed Britain his allegiance. Joyce was convicted and hanged.

Shawcross also prosecuted Klaus Fuchs, a German-born physicist convicted of giving American and British atomic secrets to the Soviet Union. Fuchs had fled Germany in the 1930s and aided British atomic research during the war.

Fuchs also worked on the American effort to build an atomic bomb _ known as the Manhattan Project _ at Los Alamos, N.M., and passed secrets from both countries to the Soviets, accelerating their own atomic program by as much as a year, according to some estimates. His espionage was uncovered in 1950, and he served nine years in prison.

Shawcross left his job as attorney general in 1951 and stepped down as a lawmaker in 1958. He was appointed to the House of Lords the following year.

He was knighted in 1945 and received an even higher honor, becoming Knight Grand Cross, Imperial Iranian Order of Homayoon, in 1974.

His son, William Shawcross, has written a number of books on contemporary history, including ``Sideshow: Kissinger, Nixon and the Destruction of Cambodia.'' Buckingham Palace said Wednesday he was chosen as the official biographer of the late Queen Mother Elizabeth.

Shawcross's first wife, Rosina Alberta Shyvers, died in 1943 and his second wife, Joan Winifred Mather, passed away in 1974.

Shawcross also is survived by his third wife, Monique, and son Hume and daughter Joanna from his second marriage. A funeral was planned for next week, Kinder said.