The writer's block that for 20 years has kept Chinua Achebe from producing a novel was not the work of the usual inner demons or fickle muse. It was, he says, the effect of something more substantial -- "one of the most horrendous wars in modern history," the bloody secessionist struggle of his fellow Ibos against the federal government of Nigeria in the late 1960s, better known as the Biafran war.

"It left me in a state of trauma," Achebe says now. "The novel seemed like a frivolous thing to be doing."

Yet this is the same man who declares, a little later, that fiction is anything but frivolous -- that it is a serious instrument of social purpose.

"The novel form is itself a political form," he says.

"All art is propaganda," he says.

Ever since the publication of his first novel, "Things Fall Apart," a much-heralded tale of African village life on the cusp of colonialism, Achebe has been propagandizing for his people through his art. He is in no way abashed about this; it's his job.

"An artist in Africa cannot avoid that involvement," he says. "If you're an African, the world is upside down. We can't conceal our dissatisfaction ... It is impossible to be neutral."

The words look more emphatic in print than they sound in his voice. Framed by a high-backed wing chair in a shadowy parlor of the Jefferson Hotel, Achebe, 57, speaks evenly, with caged politeness. He seems a little weary from a round of interviews about "Anthills of the Savannah," his new novel, and with the main event of his recent Washington visit, a lecture at the Smithsonian Institution's Resident Associate Program, still ahead of him.

With his provocative one-liners about propaganda, Achebe opens himself up to hasty judgments, and imprecise ones. In "Anthills" -- which is about propaganda, among other things -- the subject is treated with a good deal more subtlety and deliberate irresolution than the author, in person, might lead you to think.

For instance: "A genuine artist, no matter what he says he believes, must feel in his blood the absolute enmity between art and orthodoxy." So says the firebrand poet Ikem Osodi, a principal character in "Anthills," whose voice rings with authorial conviction.

Yet so does the voice of Ikem's friend Chris Oriko, the newspaper editor turned minister of information, who is as interested in survival as he is in moral purity. "Lie low for a while and this gathering tornado may rage and pass overhead carrying rooftops and perhaps ... only perhaps ... leave us battered but alive."

The tornado in question is their old school chum, who has since become president-for-life of their fictional country, Kangan, and under whose growing intolerance for dissent and disagreement Oriko and Osodi labor, together and separately, throughout the novel.

Achebe has been this way before. In the late 1950s and 1960s, the period of transition to independence in Nigeria and the rest of black Africa -- and the period of Achebe's first flowering as a novelist -- he worked as a broadcasting executive for the state-run Voice of Nigeria.

Although Nigeria then was young enough, and its leadership enlightened (or naive) enough to leave him alone, Achebe says, he does remember strange conversations with his superior in Nigeria's Ministry of Information, in which instructions were not so much dictated as implied.

Achebe understands this to be characteristic of leaders who lack the courage of their convictions. "They want you to hang around them all the time and sense what it is they want you to do," he says.

"The desire to have complete power is a recurrent problem with our leaders," he goes on, shaking his head. "They don't realize they are marginal. The real owners of the land are these millions who are not saying anything."

And who speaks for them? It is not their leaders, Achebe says, but their griots, their storytellers.

"Only the story can continue beyond the war and the warrior," a soothsaying old man observes in the novel. "It is the story, not the others, that saves our progeny from blundering like blind beggars into the spikes of the cactus fence. The story is our escort; without it, we are blind."

The same reverence for storytelling arises in the old Ibo proverb from which the novel's title derives: When the brush fires sweep across the savanna, scorching the earth, they leave behind only anthills, and inside the anthills, the surviving memories of the fires and all that came before.

Whatever his responsibilities as a propagandist, Achebe believes, the storyteller carries a license to tell stories his own way: art as propaganda, perhaps, but art first and foremost. He says he is often accused of writing "stories that end badly" and admonished to "show us people who succeed" in his books. "Well, it's absolute nonsense!" he exclaims. "The 'well-rounded tale' is not now my priority. It doesn't have to have an end. The end is the beginning of another story."

Achebe began work on "Anthills of the Savannah" 15 years ago, when he was doing a teaching stint at the University of Massachusetts in Amherst. He put it aside, half finished, for more than a decade -- during which time he wrote children's books, essays, poems, almost everything but novels -- then returned to it a few years ago "in a fever. I wrote nonstop for six months. That's very fast for me." As it happens, Achebe is back in Amherst now, doing another gig at U-Mass, as Doubleday releases "Anthills" in the United States.

In Nigeria, where the book will appear soon, Achebe has become a literary elder. Considered his country's preeminent man of letters ever since he published "Things Fall Apart" in 1958, his position may have been challenged by the selection of his younger countryman Wole Soyinka for the 1986 Nobel Prize in literature.

Asked about Soyinka, Achebe duly pays his respects, noting their political differences but stressing the importance of the prize not just to Nigerians, but to Africans. "Every fourth African is a Nigerian," Achebe observes.

Then he relaxes a little, and smiles, as he begins to repeat a conversation overheard somewhere back home:

"Who is the greatest Nigerian writer?"

"Wole Soyinka."

"Ah, and what was his greatest book?"

" 'Things Fall Apart.' "