A senior Venezuelan official has said his country's troops were not in Colombia when they died in clashes with paramilitaries near the border.
Colombia says Venezuela backs Marxist guerrillas
Authorities from the two countries are continuing to give differing accounts of the incident, worsening already tense relations.
The Venezuelans say they fired on the paramilitaries when they refused to stop at a border checkpoint.
But Colombia says its neighbour's troops crossed into its territory.
Television pictures filmed shortly after Friday's confrontation showed fuel tanks in a Colombian village on fire and houses hit by bullets.
But the Venezuelan ambassador in Bogota, Carlos Rodolfo Santiago, issued a strong denial that soldiers or aircraft from his country had gone into Colombia.
The Venezuelans insist they acted against right-wing paramilitaries on the Venezuelan side of the border.
The clash was the latest in a series of border incidents between the two nations in which at least seven Venezuelan national guardsmen have been killed.
The BBC's Jeremy McDermott in Colombia says relations between the two countries are poor as Colombian security forces believe Venezuelan President Hugo Chavez is sympathetic to - if not supporting - Colombia's Marxist guerrillas.
The left-wing rebels are known to have camps on the Venezuelan side of the border. Colombian military sources have said they believe the Venezuelans are turning a blind eye to their presence, if not actively aiding them, our correspondent adds.
The Venezuelans blame their neighbours for not patrolling their border and allowing the Colombian civil conflict to be fought on Venezuelan territory.