This semi-arid Sahelian country, one of the world's 10 poorest, has an unusually powerful labor movement that has brought down four successive governments.

Many of black Africa's rulers, fearing the power of independent trade unions, have absorbed them into the one-party governing institutions -- much as was the case until recently in Poland. The unions have been at the forefront of some of the bloodiest clashes with the colonial powers in the struggles for independence.

The latest victim of the Upper Voltan unions' wrath, deposed president Aboubakar Sangoule Lamizana, was toppled in a bloodless coup here in November after a series of strikes paralyzed his government.

Upper Volta's unions were organized shortly after World War II and have successfully resisted government efforts to limit their powers during two decades of independence from France.

The country's new strongman, Col. Saye Zerbo, 48, has warned union leaders of the 60,000-member labor force, however, that there is no money for wage increases. The military government will not tolerate strikes, Zerbo told workers in a January meeting, while it tries to reform the rampant corruption that formed part of the unions' complaints about Lamizana's government.

Many Upper Voltans and diplomats here said the coup was popular among the politically significant city dwellers, who represent only 8 percent of the 6.5 million population. Conservative Roman Catholic Cardinal Paul Zoungrana called the coup a "blessing from God." It followed months of crippling strikes by teachers, government workers, private industry employes and merchants.

The unions' grievances started with low pay but included charges of arbitrariness on the part of Lamizana's pre-coup heir apparent and former president of the now-dissolved National Assembly, Gerard Ouedraogo. The unions also complained of blatant pilfering of government funds and nepotism in the distribution of the few benefits available.

Lamizana, Ouedraogo and about 25 other former officials, including the chief justice of the supreme court, are under detention for investigation.

The deposed government was also accused of doing virtually nothing to help Upper Volta's peasant majority overcome the lingering effects of the 1968-1974 Sahelian drought.

"Corruption in a poor country like this, where there is no fat," said an international aid official, "cuts immediately into the bone. Where it may be overlooked in other countries, here you are literally taking food from people's mouths."

Another observer said that the arrested Ouedraogo had taken over most of Lamizana's presidential duties by default.

"Ouedraogo was a shrewd, Chicago-style politician of the [mayor Richard] Daley ilk who was slowly squeezing out the two opposition parties which the unions supported, and shoving a lot of opponents to the side," he said.

The Army's suspension of the three-year-old constitution ended a short-lived experiment here in a multiparty democracy. The only such government now in French-speaking Africa is Senegal. Until the coup, Upper Volta was being cited with Nigeria and Ghana as an example of a political liberalization trend in West Africa, with the military surrendering power to civilian governments.

In an interview, the new head of state, Col. Zerbo, reacted angrily to questions about his government's claims to be preserving democracy under a government that rules by edict.

"What do you think we could do?" Zerbo asked, saying Lamizana's party leaders "had given arms to their partisans with the aim of establishing power by force of arms."

Independent observers here said that Zerbo's charges have some merit.

"We were heading for a civil war situation and there was only one solution to save the nation and safeguard democratic liberties: Take power," said Zerbo. "We were responding to what the people wanted."

Upper Volta's first president, Maurice Yameogo, was toppled when the Army refused to follow his orders to open fire on strikers in Ouagadougou (pronounced wha-gah-DU-gu) in 1966 following charges of corruption and suppression of political liberties.

The crowd then proclaimed a reluctant Army Chief, then-lieutenant colonel Lamizana, as head of state. Lamizana had gone into hiding, said an Upper Voltan civilian who is close to the military government, and Zebro -- then a junior officer -- practically dragged him to a jeep to be cheered by the crowd. Lamizana "tried to get off the jeep three times, but women in the crowd pushed him back in," the source said. "Finally, he said he would stay in power for three months."

Four years later, Lamizana precipitated a general strike when he announced that the Army would not return to barracks. He backed off his position and ended the strike by bringing civilians into the government and creating a consultative National Assembly. He dismissed the assembly in 1974 and faced another general strike the following year over grievances related to the drought.

In response, Lamizana created a committee that drew up a constitution, ostensibly resigned from the Army -- but continued to live at its headquarters -- and narrowly won a three-way contest for president in 1978 elections.

Before the vote, at a meeting with Army officers, Zerbo reportedly warned Lamizana that his presence in the new civilian government would only tangle matters in the future, that the politicians supporting his candidacy were only manipulating him and that there could be a coup, preceded by another general strike, in two years.

Yet Lamizana ran for office "despite all the advice of the armed forces," Zerbo said in the interview.

Rising energy costs, inflation, corruption and an only partial recovery from the Sahelian drought gradually eroded Lamizana's popular base. The unions again became restive.

Upper Volta, about the size of Colorado, earns about $100 million during years of good rainfall, in meat, peanut and cotton exports. About 85 percent of government revenues come from duties on imports. The country also relies heavily on remittances of $70 million from the thousands of workers, 15 percent of the labor force, who live and work in prosperous Ivory Coast to the south.

Eighty percent of the government's $200 million annual budget goes to maintain the civil service, and the 5,000-member Army absorbs most of the remainder. Per capita income is $113 a year.

Zerbo, asked if there was a timetable for a return to civilian government, said, "Now our prime occupation is to avoid the mistakes of the past" and get Upper Volta on a secure economic footing.

There are those in Ouagadougou who say if Zerbo is not able to make major improvements in the country's economy soon, the unions may determine when there will be a return to civilian rule.