FREETOWN, SIERRA LEONE, AUG. 9 -- The six West African nations that plan to take part in a joint peace-keeping force to restore order to war-torn Liberia and allow Liberians eventually to choose their own leaders in free and fair elections have one key thing in common: All are ruled with a strong arm by military or civilian dictators and have little experience with democracy.

One, Ghana, is ruled by an army flight lieutenant. A second, Nigeria, is governed by a military council that booted a civilian regime out of office. Such incongruities seem to typify what nonetheless could be an extraordinary effort.

The leaders of Nigeria, Guinea, Ghana, Sierra Leone, Mali and Togo agreed this week to try to enforce a cease-fire in the eight-month-old civil war, which has claimed the lives of at least 5,000 Liberians, spawned tens of thousands of refugees and devastated the nation's economy.

The Mediation Committee of the Economic Community of West African States, in announcing the peace-keeping force, said it hopes the effort, which is to be led by a Ghanaian general, will lead to the convening of a conference of all parties to the Liberian conflict, the establishment of an interim government and eventual elections.

Today, the president of Sierra Leone, an army major general named Joseph Momoh, exhorted his troops to bring peace to Liberia and expressed a deep desire to join them himself in a speech in a mountaintop barracks here today.

But while the lofty goals of the joint force have been lauded here and throughout Africa as a preeminent example of regional cooperation, no one has yet said when the force will form or be deployed, and what it will do when and if it encounters resistance from rebels of the National Patriotic Front.

The rebels, who started the civil war with a Christmas Eve invasion and feel they are on the verge of overthrowing President Samuel K. Doe, have vehemently opposed the idea of West African intervention to stop the fighting. Doe's government, or what remains of it, and a breakaway rebel faction welcomed the intervention plan, however.

Today, in an ominous development that may signal an initial expression of the Patriotic Front's opposition to the peace-keeping force, more than 300 Nigerian nationals who had sought haven in the Nigerian Embassy in Monrovia were ordered out of the building at gunpoint by the rebels. The incident sparked a protest by the Nigerian foreign minister, who said today that Nigeria would remain neutral in the conflict unless, and until, "a Nigerian life is lost."

Troops from Nigeria, the most powerful member of the West African economic community, will form the largest part of the force.

Monrovia, wracked by anarchy and filled with the stench of decaying bodies, is already a tense and volatile place. Some observers fear that to insert yet another force into this mix may cause more harm than good. In addition to government and rebel troops, a contingent of U.S. Marines is guarding U.S. government property in Monrovia.

{A spokesman for Doe said Thursday that U.S. Marines in a helicopter fired on Doe's mansion in an attempt to assassinate Doe, the Associated Press reported. The State Department denied that any such incident took place.}

The fact remains, however, that with refugees continuing to spill over into the impoverished neighboring countries of Sierra Leone and Guinea and with West African and other foreign nationals in harm's way in Monrovia, the war has already assumed regional proportions.

"We must try to help our nationals. We must try to save that country," said Anthony K. Twumasi, Ghana's ambassador to Sierra Leone and a brigadier in the Ghanaian army who is a member of the joint West African committee planning the military intervention.

Africans "always look to the outside for help, economically and politically," he said. "I think it's time we came of age to take our destiny in our own hands."