A leading commander of the Colombian rebel group FARC, Raul Reyes, has been killed in combat in a southern province along the frontier with Ecuador.
Defence Minister Juan Manuel Santos said Mr Reyes was killed in an air raid that was followed by a ground operation that left 18 militants dead.
Mr Reyes was one of the seven members of the secretariat of the Revolutionary Armed Forces of Colombia, or FARC, Latin America's oldest surviving left-wing insurgency, which US and European officials label a terrorist group.
The death of one of its top commanders is the most serious blow to the FARC under the government of President Alvaro Uribe, who has received billions of dollars in US aid to fight the rebels and cocaine traffickers.
‘This is the most important strike yet delivered against this terrorist group, Mr Santos said.
Violence from Colombia's conflict has ebbed under Mr Uribe, who has sent troops to retake areas under the control of armed groups.
But the FARC is still potent in remote areas, where it is holding scores of hostages including three US contract workers and French-Colombian politician Ingrid Betancourt.