Rebels launched a series of attacks on military units across the country in apparent retaliation for army operations in guerrilla zones of control during an election truce, the army said.

"We are seeing an increase in guerrilla activity in several provinces," a military spokesman said Thursday. Combat between government troops and rebels of the Farabundo Marti National Liberation Front, or FMLN, had intensified dramatically in the past few days, he said.Ten rebels and three soldiers died in fighting in the eastern provinces of San Miguel, Morazan and La Union, the spokesman said.

Political analysts in San Salvador said the FMLN was retaliating against the armed forces for last weekend's massive army operations in rebel strongholds during a three-day unilateral rebel cease-fire to honor Sunday's elections.