A powerful bomb was discovered in the main Arlington post office yesterday in a cigar-box-sized package addressed to the leader of a local Nazi-styled organization.

Authorities said the bomb, safely disarmed by Army explosive experts shortly after its discovery, was one of at least five mailed recently to individuals around the country identified with past or present Nazi activities. No injuries have been reported.

If the bomb found here had exploded, "anyone within 10 feet could easily have been killed," an Army bomb squad member said.

The bomb was taken apart behind the past office on Washington Boulevard using a remote controlled device whose method of operation bomb squad members declined to discuss.

They said only that the device produced a "controlled explosion" that disrupted the bomb's firing train," and prevented the actual bomb from exploding.

Witnesses said the controlled explosion was heard for a block around and hurled splinters of debris for 25 feet.

The package, wrapped in a manila envelope, was discovered about 3:40 p.m. afteh the Postal Service issued an alert about suspecious packages. It was addressed to Matt Koehl, commander of the National Socialist White People's Party at party headquarters, 2507 N. Franklin Rd., Arlington.

Espousing antiblack and anti-Jewish doctrine, the party is the successor to the American Nazi Party led by George Lincoln Rockwell, who was fatally shot in 1967.

Party members have adopted symbols and dress reminiscent of Adolf Hitler's Nazi Germany.

The FBI and postal authorities said the bomb found here, along with others received or discovered since Friday in Paterson, N.J., Cicero and Chicago, Ill., and Lincoln, Neb., was being investigated.

Both the Associated Press and United Press International reported receiving calls asserting that bombs had been sent. AP said it heard from callers claiming to represent the International Committee Against Nazism. UPI said it was called by persons claiming to represent The Jewish Action Movement.

A spokesman for a small New York group with the same name as the one that purportedly called AP described his organization as nonviolent and denied any involvement.

AP said it was told in a call yesterday that the locations of the bombs had been revealed because "this is only a warning . . . There'll be more tomorrow."

A bomb was reportedly received in the mail Friday in Paterson by a man identified by the AP as a former Nazi SS officer.

The bomb sent to Cicero was defused after it was received by its addressee, the midwest headquarters of the National Socialist White People's Party, according to the AP.

Chicago police said a bomb found at a post office there was addressed to Frank Collin, head of the National Socialist Party of America. Collin threatened last year to hold a highly controversial Nazi in Skokie, Ill., a heavily Jewish suburb of Chicago.

Explosive technician Donald Kenney said the black powder bomb found in Chicago was contained in a 9-inch-by-2-inch-by-6 1/2-inch cigar box with an electrical detonator.

It came in an envelope bearing $4 in postage and postmarked in New York last Thursday, he said.

In Lincoln, Neb., another cigar box bomb was disposed of Sunday after it was received by a man identified as a "member of a Nazi organization," according to police Lt. Ron Bruder.

The recipient was not expecting mail from New York and "got suspicious," Bruder said. The bomb, he added, "could have been deadly."

The manila envelope that contained the Nebraska bomb also held a sheet of paper bearing the words: "dear friend," Bruder said.

In Arlington, members of the Fort McNair-based bomb squad said the device sent here was designed to explode when the box was opened.

After the device was successfully disarmed, its pieces were collected by postal inspectors, according to Capt. Jack Edwards, head of the bomb squad.

Koehl, the intended recipient of the package, was reported out of town yesterday.