The curious thing is that Harry Belafonte does not sound bitter, even when he is talking of disappointed hopes, lost opportunities, hard times ahead -- even when he is leveling serious charges about CIA infiltration of the Peace Corps in Africa in the '60s. He is in his hotel room at the Tyson's Corner Marriott, a few miles away from CIA headquarters. He is relaxed, and when he smiles -- which is often -- he is still one of the world's handsomest men.

An experienced interviewee, Belafonte fends off personal questions with quick, unsolicited answers: "I sleep without pajamas, I have no pets and my private life is private."

Belafonte made his first impact before the rock revolution; he broke the 39-year attendance record in New York's enormous Lewisohn Stadium in 1955, and in the same era he established records, many of which still stand, in halls all over the United States. He sang everything from Calypso to British music-hall tunes and Appalachian folk songs, but he was most closely identified with music of the Caribbean, where he was born. His face decorated the covers of millions of record albums, and drove millions of women to distraction.

A generation of college-age admirers grew up humming "Day-O, Day-O" and "Matilda, Matilda, she took the money and run Venezuela" in harmony with his records. With Pete Seeger and Woody Guthrie, but in a much more exotic style and with enormously more sex appeal, he helped to launch the folk-song revolution of the '50s and early '60s, paving the way for such performers as Joan Baez and Bob Dylan.

In a world where the Beatles are already more legend than reality to young people, Harry Belafonte's career is still going strong, though he maintains a relatively low profile. His appearances in Washington have been infrequent in the last few years -- most recently a benefit performance for TransAfrica two years ago in Constitution Hall. He can sing pretty much when and where he chooses, and at the end of his current tour, he plans to take two years off. He will be working on a new project: preparing a Broadway production of a musical on the legendary black street-fighter, Stagolee. He is looking for dramatic material "that will tell the story of blacks the way 'Fiddler on the Roof' told about Jews."

Now, he is in the middle of a 71/2-month world tour which has already taken him to Australia and the Far East and will go on to Europe in a few weeks; he is about to have a new album, "Loving You Is Where I Belong," released by CBS; and he will be featured as a football coach in a television movie, "Grambling's White Tiger," scheduled to play as an NBC Movie of the Week in December. Personally, he could hardly be happier, even though he has grown a few gray hairs.

He also has a young granddaughter, Rachel Bieseneyer, who is visitng him with her mother, Adrian, from their home in West Virginia. It may be hard to image Harry Belafonte as a grandfather, but he says "I love it" with the familiar husky vibrato that has made his voice one of the best-known in the world.

What Belafonte does not love is what is happening musically between America and the Third World. He has been an apostle of African, Caribbean and Latin American idioms in music since he became an international star in the mid-1950s -- not only in his own singing but in his sponsorship of singers such as Miriam Makeba and Letta Mbulu, a young South African from the Xhosa tribe who is touring with his company. He was one of the leaders in the surge of black talent that made an impact on the American media in the wake of the civil rights movement. He personally undertook a massive program to develop a touring African dance company, and now he sees all these promising beginnings and others withering away in a tide of reaction.

"The process is being reversed in Hollywood and on television," he says. "All that I had hoped for is threatened. On my television set, in an entire week, the definitive black presentation is in the hands of "The Jeffersons." It's appalling, not only because the show is singularly offensive but because there is nothing there to balance the diet. We may have a second cop in a police show, a fleeting presence in a soap opera, an occasional newscaster or anchorperson -- and, of course, lots of people in sports -- but there is no real black presence, nothing that truly reflects the richness and variety in the lives of 23 million Americans."

He puts part of the blame on the media and part on his fellow black artists who scored personal triumphs without using their own success to open the door for others and establish solid bases to build for the future. After early approaches to movies and television, he recalls, "we concluded that to turn the media around we would have to turn the country around." This was done in the civil rights movement. "When it began to open up," he says, "I told people, 'We need to establish solid institutions, give our young artists a place to grow and a place to come home to.' It didn't happen. I turned down parts that I considered meaningless, unrewarding, even demeaning, and I saw others take them and get swept into the Hollywood mystique. They became totally preoccupied with material possessions, bought big houses and started worrying about how to pay the mortgage, and now they are having trouble finding work. The black community had a good chance to launch a renaissance. Our talk was the talk of the country, our comedians were making people laugh with them, we were beginning to have an impact in a very favorable way, and now it is being reversed. I learned long ago, as a student, that progress is made by taking two steps forward and one step back, but I'm afraid that with Ronald Reagan in the White House we may be taking 100 giant steps back. I am not at all convinced that America will never become a police state."

His project in the African country Guinea, which was undertaken with assistance from the Peace Corps, folded up after African governments learned that the CIA was using some other Peace Corps projects as cover. The folk idioms from around the world that he was putting at the top of the top-40 lists 20 years ago were drowned in the tidal wave of rock, which swept from America across the world. Belafonte talks sadly about Japanese and African musicians whose chief ambition is to sound like Americans, and the difficulty of introducing foreign idioms into America. "We came close with reggae," he says, "but whenever you want Americans to work a little, you begin to lose them."

Opportunism is the problem, he feels, not only in the media but in some of the black performers who have found a place in the media. "WE could not just harvest; we had to really care for the land. We had to turn it over, be sure that we did not rape it. And what we did was everybody went out there and harvested and nobody tended. And now we're looking back, the weeds have grown, the land lies fallow and what we have to do is go out and invigorate it, start to prime it all and hope for new growth."

In a sense, he finds grounds for hope in the extremes to which he sees the Reagan administration going. "Let him go as far as he can," Belafonte says. "I hope he keeps on going, because he is opening the possibility of new coalitions we could never have dreamed of. Who could ever have imagined the possibility of ann alliance between Third-World forces and the air traffic controllers. Now, that looks like a real possibility."