HAVANA: Colombia's government and leftist FARC rebels signed a final peace deal on Wednesday to end a 50-year-old guerrilla war, one of the world's longest conflicts which took the resource-rich country to the brink of collapse.

The two sides said they had reached an agreement to end the conflict and build a stable peace, in a joint statement read out by representatives of Cuba and Norway, who are mediators in the talks.

"We have arrived at a final agreement... for an end of the conflict and the construction of a stable and lasting peace in Colombia," said Cuban representative Rodolfo Benitez, reading from the statement before the agreement was signed by lead negotiators for the rebels and the government.

The historic accord foresees the demobilization of the Revolutionary Armed Forces of Colombia (FARC), whose cocaine-funded rebels fought the government in a war that killed at least 220,000 people. Tens of thousands disappeared and millions fled their homes because of the violence.

The deal, opposed by two former Colombian presidents, still needs to be voted on in a referendum before it becomes law.

Most opinion polls suggest Colombians will back it. Still, Santos, who has staked his legacy on peace, will have to fight hard for a "yes" given fierce opposition from powerful sectors of the country who think the only solution is to crush the FARC militarily.

"A positive vote once seemed like a slam dunk," said Tom Long, International Relations lecturer at Reading University.

"But opposition from former presidents (Andres) Pastrana and (Alvaro) Uribe will force Santos to campaign hard for the accord."

A previous round of talks, under Pastrana between 1999 and 2002, collapsed after the guerrillas hijacked an airplane.

The two sides signed a ceasefire in late June, including guidelines on how the FARC would lay down weapons.

Since then talks have focused on the rebels' future political participation, the reintegration of fighters into civil society, and details on how the international community will monitor the implementation of the agreements.

BOON FOR BUSINESS

An agreement with the FARC does not guarantee an end to violence that began as a peasant revolt. Talks between the smaller, leftist National Liberation Army and the government recently stalled. Gangs born out of right-wing paramilitary groups are reported to have taken over some of the FARC's drug trafficking routes.

But an agreement is a prerequisite for peace. A ceasefire has already sent violence to its lowest level in decades.

The improved security should boost investment and tourism and could open up development in rural regions of the emerging markets darling, analysts say, estimating a 0.3 percent to 1 percent increase in economic growth.

"If you have an improvement in overall security, foreign and national investment increases," said Sabine Kurtenbach at the Hamburg-based GIGA research institute.

Key to securing a sustainable peace is that extra economic growth benefits Colombia's poorer, rural areas, analysts said.

The FARC was born, like many other Marxist-inspired peasant insurgencies across Latin America in the 1960s, out of frustration with deep socio-economic inequalities.

Funded by cocaine and kidnappings for ransom, it grew to a 17,000 strong force operating across vast swaths of Colombia.

While other Latin American insurgencies were crushed by right-wing governments or convinced to join conventional politics by the 1990s, the FARC was still going strong.

This only started to change when Uribe in 2002 launched a US-backed counterinsurgency campaign that killed many FARC leaders and reduced its ranks to an estimated 7,000 fighters.

Uribe says the government is giving in to "terrorism" by negotiating with the FARC and granting it a degree of amnesty. His party, Colombia's main opposition group, announced earlier this month it would back a "no" vote in the referendum.

Under accords already struck in Cuba, perpetrators of the worst crimes will face "transitional justice" aimed more at finding out the truth than administering harsh punishment.