Nazi Germany's deputy fuehrer Rudolf Hess, who for nearly 21 years was the sole inmate of a 600-cell prison guarded by troops of the World War II allies, died yesterday in West Berlin at 93. The cause of his death was not announced.

Spandau prison, where Hess was a prisoner for 40 years, "will be demolished" at an unspecified time, according to a statement of the four powers that occupy Berlin -- the United States, Britain, France and the Soviet Union.

"The purpose of Spandau Allied Prison has ceased on the death of Rudolf Hess," the statement said.

Contingents of 100 soldiers had guarded the prison on monthly duty rotated among the four powers. The last of Hess' fellow Nazi inmates were released in 1966.

Hess, called "the loneliest man in the world" by an American ex-commandant of Spandau prison, Eugene K. Bird, had been behind bars since 1941, when he made a mysterious solo flight to Scotland. He was sentenced at Nuremberg in 1946 to life imprisonment.

Reaction yesterday to Hess' death was terse. The State Department and the Soviet Union issued similar statements, announcing his death without comment and calling him one of the major Nazi war criminals.

Communist East Germany gave a one-sentence announcement of Hess' death, but the West German government declined to comment. A West German television network said those who lived through World War II will "feel a certain relief at the news."

"Justice sometimes grinds exceedingly slow but it does catch up in the end," The Anti-Defamation League of B'nai B'rith said. "Hess' death closes another chapter in the infamy that was the Holocaust. Hess was a living symbol of that infamy." @Caption:Hess has been Spandaus'only occupant since 1966.