PÉHÉ-KANHOUÉBLI, Ivory Coast — Standing by a burned-out house on a road speckled with spent ammunition casings, Brig. Gen. Gueu Michel, the commander of rebel forces in western Ivory Coast, outlined his plan to stem an influx of Liberian mercenaries he said were fighting for Ivory Coast’s embattled strongman, Laurent Gbagbo.

“Gbagbo’s troops are composed of the Ivorian Army, the Liberian mercenaries and the militia,” he said recently, pointing to a carefully folded map. “We want to cut off the mercenary flow into Côte d’Ivoire.”

But the traffic at the border moved in two directions. As General Michel’s troops gained ground, a tide of refugees escaping the crisis crossed the porous and remote border into Liberia, a country with a fragile grip on stability itself.

According to the United Nations, more than 100,000 people have fled to Liberia, an exodus visible in the women with bundles on their heads and babies on their backs, trudging on or sitting exhausted by trail sides. And as the struggle over Ivory Coast spills beyond its borders, many fear it will rattle a region still trying to recover from its own history of civil war.