At least five soldiers were killed and six wounded when they stumbled onto a minefield in southern Colombia, near the border with Ecuador, officials said.
"It was a cowardly act by FARC terrorists," Defense Minister Gabriel Silva told reporters in Medellin, Colombia's third largest city, a day after the bombing incident in Putumayo department.
A military spokesman in Putumayo said the leftist Revolutionary Armed Forces of Colombia (FARC) had laid anti-personnel mines in a field near the village of Alto Lorenzo where they knew a military patrol would be passing.
The incident occurred just as President Alvaro Uribe was visiting the region on Friday, although officials stressed he had not been at risk.
Clashes between rebels and the military are frequent along the Colombian-Ecuador border, as FARC guerrillas cross it to escape from pursuit.
Rebel activity has picked up in anticipation of the May 30 presidential election that caps Uribe's two presidential terms, his last day in office is August 7, and the rebels hope, his "iron-fisted" crackdown against the FARC.