Colombia’s civil conflict spans more than four decades and has drawn in left-wing rebels and right-wing paramilitaries.
Here are profiles of the three main armed groups:
REVOLUTIONARY ARMED FORCES OF COLOMBIA (FARC)
The Farc is the oldest and largest group among Colombia’s left-wing rebels - and is one of the world’s richest guerrilla armies.
The group was founded in 1964, when it declared its intention to use armed struggle to overthrow the government and install a Marxist regime.
But tactics changed in the 1990s, as right-wing paramilitary forces attacked the rebels, and the Farc became increasingly involved in the drug trade to raise money for its campaign.
Some analysts believe the group has lost its political vision and that drugs have changed the way it fights. Kidnapping and extortion are now often an end in themselves.
The Farc, which is on US and European lists of terrorist organisations, suffered a series of blows in 2008.
Perhaps the most serious to date was the 2 July rescue by the military of 15 high-profile hostages, including the former presidential candidate Ingrid Betancourt.
The hostages had long been seen as a key element in the rebels’ attempts to exchange their captives for jailed guerrillas.
On 25 May, the guerrillas confirmed that their top commander, Manuel Marulanda,had died of a heart attack two months earlier.
Also in May, a female commander Nelly Avila Moreno, known as Karina, surrendered and then called on other rebels to follow her example, saying the Farc was falling apart under military pressure.
Marulanda’s death followed the killings of two other members of the rebels’ seven-member secretariat in March.
Raul Reyes, seen as the Farc’s number two,was killed in combat, government officials said, while days later rebel commander Ivan Rios was killed by a fellow guerrilla who then turned himself in.
The Colombian government insists it is winning against the Farc and has called on the rebels to enter peace talks.
Some analysts say the guerrillas are finished as a potent force, although they may fight on, perhaps as a smaller and more divided insurgency, and still involved in the cocaine trade.
President Alvaro Uribe, who swept to power in 2002 vowing to defeat the rebels and was re-elected in 2006, launched an unprecedented offensive against the Farc, forcing them to retreat from urban areas.
The rebels still control large areas in the south and east, where the presence of the state is weak.
The group had about 16,000 fighters in 2001, according to the Colombian government, but some reports suggest their numbers are now down to about 9,000.
NATIONAL LIBERATION ARMY (ELN)
**The left-wing group was formed in 1965 by intellectuals inspired by the Cuban revolution. **
The ELN has been behind many kidnappings in Colombia, snatching hundreds of people each year to finance its operations. But over the past three years, the group has become involved in drug trafficking, according to Colombian government officials.
The group has focused on hitting infrastructure targets such as the oil industry, because it has been unable to take on the security forces directly like the Farc.
The ELN reached the height of its power in the late 1990s, but in recent years has been hit hard by the paramilitaries and Colombian armed forces.
There have beenseveral rounds of exploratory peace talks with the government in recent years, held in the Cuban capital, Havana, but no concrete progress.
Nicolas Rodriguez Bautista is top commander of the group, which operates mainly in north-eastern Colombia and is thought to have between some 3,000 members.
The group is on US and European lists of terrorist organisations.
UNITED SELF DEFENCE FORCES OF COLOMBIA (AUC)
**This right-wing umbrella group was formed in 1997 by drug-traffickers and landowners to combat rebel kidnappings and extortion. **
The AUC had its roots in the paramilitary armies built up by drug lords in the 1980s, and says it took up arms in self-defence, in the place of a powerless state.
Critics denounced it as little more than a drugs cartel.
The AUC’s influence stemmed from its links with the army and some political circles, and its strength was boosted by financing frombusiness interests and landowners.
The group has carried out massacres and assassinations, targeting left-wing activists who speak out against them.
The US and EU list the AUC as a terrorist organisation.
The paramilitaries declared a ceasefire in 2002.
A2003 peace deal saw paramilitary leaders surrender and demobilise 31,000 of their men in exchange for reduced jail terms and protection from extradition.
Nevertheless, the peace process has been beset by hurdles such as ceasefire violations and the paramilitaries’ demand for amnesty.
In May 2008, the Colombian authorities extradited 15 former paramilitary leaders to the US to face drug trafficking charges, saying they had violated the terms of the peace deal.
In another development, inquiries have been opened into dozens of current or former members of congress over their alleged ties to the AUC in what has been dubbed the “parapolitics” scandal.This article is from the BBC News website. © British Broadcasting Corporation, The BBC is not responsible for the content of external internet sites.