A strained silence fell over the audience at the University of Ibadan book-launching ceremony as Oyo State Gov. Bola Ige accused of quick-tempered guest of honor of cheating the Unity Party of Nigeria out of last year's race for president.

Seated directly to the right of the standing Ige, the former military head of state, retired Gen. Olusegun Obasanjo, failed to mask the flash of anger at Ige's charge. The often-repeated allegation presents the most serious domestic challenge to the year-old civilian government of President Shehu Shagari.

Shagari's supporters have denied that the former military government favored them and in turn have charged that supporters of the presidential contender Obafemi Awolowo were caught stuffing ballot boxes.

In an African nation such as Nigeria, whose nearly 100 million people consist of 250 ethnic groups, such fiery political antagonism can spark civil disorders. Each of the five political parties has a strong regional and ethnic base.

In spite of constant verbal attacks by Awolowo's Yoruba-based Unity Party, however, Shagari's low-key approach to civilian government after 13 years of military rule has avoided the provocations that proved destructive in the past.

In the mid-1960s, similar charges of election fraud provoked such wide-spread rioting among the Yoruba people in the region surrounding Ibadan that the Army coup that followed was greeted with collective relief.

But the nature of the coup, seen as dominated by the Ibo people, pushed the country into civil war and extended military government through two more coups and one bloody attempted coup.

In the recent irony-filled public confrontation between Ige and Obasanjo, both Yorubas, the memories of those strife-ridden years were not far away. Ige had been detained at the height of the 1960s violence, and Obasanjo emerged from the civil war a military hero pained by the misery and destruction the war had wrought.

Ige had been invited to the campus function to give a critique in launching Obasanjo's civil war memoirs, "My Command."

In the process, he leveled his charge. "It is also well known that I and the political party to which I belong do not forgive [Obasanjo] for the part we believe he played in rigging us out of success in the 1979 elections," Ige said above an audible aspiration from the 300 people attending.

In response, Obasango said, "Governor Ige would not be here today if the military had toyed in any way with the 1979 general election results. We were absolutely impartial."

In a clear reference to what could be expected if the friction between the United Party and Shagari's government were to escalate out of control, Obasango concluded that "those who have seen war in its true nakedness and watched the ravages of war in tears will be the last to wish anything similar to war for their community."

As the most populous and most powerful country in black Africa, Nigeria is a trend setter.

On the surface, the basis of today's conflict over last year's presidential election was the outcome of the constitutional court battle between Shagari and Awolowo on how the results were to be counted.

But the deeper question for many Nigerians was style of leadership -- that of the 70-year-old, uncompromising, acerbic, populist Awolowo, with a strong ethnic base among Yorubas in the south, or of Shagari, 55, a technocratic northern Fulani who was a conservative consensus candidate and whose support cut across tribal lines.

In popular votes, Shagari outpolled Awolowo 5,688,857 to 4,916,651, but the Nigerian constitution requires a winning president candidate to take at least 25 percent of the vote in two-thirds of the 19 states.

That clause attempts to ensure that any president candidate appeal to the entire nation. None of the country's three major ethnic groups -- the southwest Yoruba, the southeast Ibo, and the northern Hausa-Fulani -- dominates more than five states. The three groups make up 60 percent of Nigeria's population.

Shagari won more than 25 percent of the vote in 12 states but received only 19 percent in a 13th. Awolowo did much more poorly, winining more than 25 percent in only six states. The Nigerian electoral commission declared Shagari the winner, adding the interpretation that two-thirds of 19 amounted for election purposes to 12 rather than 13 states, as had been generally thought.

awolowo cried foul, challenged the decision in court and lost. He has constantly charged that the outgoing head of state and fellow Yoruba, Obasanjo, influenced the commission and the court to prevent the election from being thrown into the electoral college.

Awolowo's widely circulated newspaper, The Daily Tribune, has kept up a tirade against Shagari's government and his National Party of Nigeria.

Until recently, even the governors of the five southwestern Yoruba-dominated states -- Oyo, Ondo, Ogun, Lagos and Bendel -- maintained an openly hostile posture toward Shagari's government.

Meanwhile, critics of Awolowo have argued that his party was built "on a personality cult" and that he is trying to "incite" the population in an effort to destablize the government.

In a recent interview with an indepedent daily, The Punch, Awolowo dismissed such accusations.

"A major crisis in an ill-wind that blows no one any good," Awolowo was quoted as saying. "I pray that there is no military coup in this country again, because if there should be one, it will be bloody.

"I still have aspiration but not a burning ambition to be president of Nigeria," he added.

Shagari has made efforts to court all ethnic groups. When torrential rains last August left more than 200 persons dead and 50,000 homeless in this city, Shagari came a week later to inspect the damage.

"That was one of the best judgments he ever made," said Gov. Ige, who escorted Shagari through the city that is Awolowo's political stronghold.

Shagari ordered that $5.5 million in federal money be given to Ibadan for flood disaster relief. "I didn't care about the money," said Ige. "I care about [the show] of concern."