|At its height, the Farc was estimated to have some 20,000 active fighters (Image: 1999)|
President Juan Manuel Santos hailed it as a "the first step towards the consolidation of peace" with the left-wing Farc guerrilla group.
The amnesty is part of a revised deal agreed after the original pact with the Farc was rejected in a popular vote.
The conflict has killed more than 260,000 people and displaced millions.
The law will offer freedom from prosecution for some junior members of the Farc, the country's largest rebel group - and for some army soldiers. But in both cases they must only be accused of minor crimes.
Thousands of guerrilla fighters who are accused of minor crimes stand to be pardoned under the law.
The original peace deal, rejected at a referendum on 2 October, was seen by many as too lenient towards the rebels.
The government and the Farc then went back to the negotiating table to try to strike a new deal acceptable to those who had voted "no".
The main amendments included:
- The Farc will have to declare all their assets and hand them over. The money will be used for reparation payments for the victims of the conflict
- Concerns by religious groups that the agreement undermined family values have been addressed
- A time limit of 10 years has been set for the transitional justice system
- Farc rebels will be expected to provide exhaustive information about any drug trafficking they may have been involved in
- The peace agreement will not form part of Colombia's constitution
The revised peace deal was ratified by Congress on 1 December. It is not due to be submitted to a popular vote.
Mr Santos has been awarded the Nobel Peace Prize for his part in the negotiations.
Colombia approves amnesty deal for thousands of Farc rebels
Colombia’s Congress has approved an amnesty law to protect thousands of demobilising Farc guerrilla fighters from prosecution for minor crimes committed during the country’s 52-year war.
The law, a key part of a peace deal signed last month between the government and the Revolutionary Armed Forces of Colombia rebels, will not include those who have committed war crimes or human rights violations.
The amnesty also applies to members of the country’s military. It is the first in a series of laws tied to the deal that will be pushed through Congress in the hope of reassuring rebels who are beginning to move to special demobilisation zones.
The bill passed in the Senate and the lower house, despite vociferous opposition from the right-wing Democratic Center party, whose members abstained from voting. The coalition of President Juan Manuel Santos, who was awarded the Nobel peace prize this month, has a majority in Congress.
About 7,000 Farc fighters are expected to lay down their arms over the next six months.
Rebels found guilty of serious crimes such as massacres, sexual violence or kidnapping will not fall under the amnesty and will instead serve alternative sentences such as land mine removal, to be determined by a special court.
In a joint statement on Wednesday, the Farc and the government said they would establish how many rebels were not eligible for the amnesty by 30 January at the latest.
Other laws tied to the peace deal include rural reform, compensation to victims, removal of land mines and a United Nations-monitored ceasefire. The Farc will convert into a political party under the accord.
Lawmakers in Colombia pass FARC amnesty law
Bogota (AFP) - Colombia's Congress passed a law granting amnesty to FARC rebels as part of the country's peace deal, a development the government hailed as "historic."
"Thanks to the Congress which in a historic vote approved the amnesty law, first step toward consolidating peace," President Juan Manuel Santos said on Twitter.
The measure grants special legal treatment, amnesty and pardon to members of the Revolutionary Armed Forces of Colombia (FARC) accused of political and related crimes.
The Senate passed the bill 69-0, after the House of Representatives approved it 121-0.
The amnesty bill is part of the November 24 pact aimed at ending five decades of conflict.
Former president Alvaro Uribe spearheaded opposition to the peace deal after nearly four years of negotiations to end more than half a century of armed conflict.
The former president and his allies argue the deal grants impunity to rebels guilty of war crimes, giving them seats in Congress rather than sending them to prison.
After voters rejected the earlier deal by a narrow margin, the government and the FARC renegotiated it, deciding to have it ratified in Congress rather than risk a second referendum.
The conflict has killed more than 260,000 people and left 45,000 missing.