Dexter Scott King, the younger son of the Rev. Martin Luther King Jr., yesterday called on Americans of all races and cultures to make the federal observance of his father's birthday a symbol of unity among individuals and of the struggle for world peace and justice in South Africa.

"We must learn to live together as brothers or we shall all perish together as fools," King told several hundred employes of the U.S. Department of Health and Human Services and the U.S. Information Agency at a commemoration yesterday, one week before the first King federal holiday.

"All people of good will can relate to his message. He talked about peace, he talked about love," the 24-year-old King said of his father, who was awarded the Nobel Peace Prize in 1964. "We must make this holiday an all-American holiday." The ceremony, held in the large entrance hall of the Hubert H. Humphrey Building, was attended by a standing-room-only crowd.

Recently instated HHS Secretary Otis R. Bowen paid tribute to Martin Luther King Jr., assassinated in 1968 in Memphis, as a "historic peacemaker" whose legacy was "the challenge of service and the challenge of self-reliance."

"Let's not only remember the man who labored for the social progress we enjoy but let's remember his message, and with that memory rededicate ourselves to the values of self-reliance and service," he said.

The commemoration was just one of a number of federal and local tributes scheduled for the coming week, leading up to the federal holiday next Monday, when most federal and local government workers will have the day off. On Thursday federal employes selected by their agencies will attend a rally and tribute at the Department of Commerce in its 1,200-seat auditorium.

At yesterday's commemoration, Stanton H. Burnett, counselor of the U.S. Information Agency, recalled that those Americans whose jobs took them overseas in the 1950s and 1960s knew that throughout the world King's name "was synonymous with progress, or lack of it, in social developments in the United States."

"He seemed to be speaking not merely for the civil rights movement in the South but for every man and woman everywhere who had been victimized," said Burnett, who worked for the USIA in the Congo, now Zaire, when King was shot. Referring to letters on oppression that King wrote from the Birmingham jail, Burnett said: "Wherever injustice exists, as it does so blatantly in South Africa today, people read and are inspired by these words."

Dexter King said his father's work should continue in the fight against poverty and world hunger and for self-determination in South Africa.

"If he were alive today, he would say we still have the job ahead of us, because no man is free until all men are free," King said.

Sitting in the third row, HHS employe Nellie Reese said she reflected on the profound impact the civil rights leader had on her as a black woman born in the South and educated in the North. She heard Martin Luther King Jr. deliver his famous "I have a dream" speech during the March on Washington in 1963 and still listens to him on a recording.

"Any meaningful position that any of us have would have to stem from some of the work that he did. It gave us the zest and the desire to say, 'Yes, I can,' " Reese said. "It's a part of me, and I want it to be a part of my children and their children."