BOGOTA - Colombia's president is moving fast to hold a plebiscite on a landmark peace deal reached with leftist rebels, presenting to congress Thursday the full text of the accord that he says will end a half-century of bloody combat.

"Today is the beginning of the end to the suffering, pain and tragedy of war," President Juan Manuel Santos said Wednesday night in a televised address after the deal was announced in Havana, where talks went on for four years. He said he would hold an Oct. 2 yes-or-no vote on the accord with the Revolutionary Armed Forces of Colombia.

He planned to make the full text of the accord public Thursday as it is formally delivered to congress, which cannot block the plebiscite.

"It's in your hands, of all Colombians, to decide with your vote to support this historic accord that puts an end to this long conflict between the children of the same nation," he said.

As Santos spoke, some 400 residents of Colombia's capital gathered at a plaza to celebrate the country's best chances of closing out decades of political violence that killed more than 220,000 people and driven more than 5 million from their homes. Several carried candles and were dressed in white to symbolize peace while a giant red, blue and yellow national flag was carried through the crowd.

"I can die in peace because finally I'll see my country without violence with a future for my children," Orlando Guevara, 57, said tearfully.

Negotiators reached the accord after working around the clock for several days hammering out the final sensitive details left to the end of the talks.

Among last-minute concessions were guarantees that the FARC's still unnamed political movement will have a minimum of 10 seats in congress for two legislative periods. After 2026, the former rebels will have to prove their political strength at the ballot box

"We've won the most beautiful of all battles: the peace of Colombia," the chief FARC negotiator, alias Ivan Marquez, said at the announcement in Havana.

As soon as his speech finished, the emotional crowd on the plaza in Bogota sang the national anthem and shouted "Viva Colombia! Yes to Peace!"

Congratulations poured in from the United Nations, which will play a key role keeping the peace, and regional governments. U.S. President Barack Obama also welcomed the deal.

The accord commits Colombia's government to carrying out aggressive land reform, overhauling its anti-narcotics strategy and greatly expanding the state's presence in long-neglected areas.

The FARC were forced to the negotiating table in 2012 after a decade of heavy battlefield losses inflicted by the U.S.-back military. Several top rebel commanders were killed and its ranks thinned by half to the current 7,000 guerrillas.

Overcoming decades of animosity will be tough: Polls say most Colombians loathe the rebel group and show no hesitation labeling them "narco-terrorists" for their heavy involvement in Colombia's cocaine trade, an association for which members of the group's top leadership have been indicted in the U.S. But surveys also indicate Colombians will likely endorse a deal.

Santos, an unlikely peacemaker given his role as architect of the military offensive that battered the FARC, maintained a steady pulse throughout the negotiations even as he was called a traitor by his conservative former allies and suffered a plunge in approval ratings.

The most contentious breakthrough came last September when Santos travelled to Havana to lay out with FARC commander Rodrigo Londono a framework for investigating atrocities, punishing guerrillas for involvement in those abuses and offering compensation to victims.

Opponents of Santos and some human rights groups harshly criticized a key part of that deal which would let rebels who confess their crimes avoid jail and instead serve reduced sentences of no more than eight years by helping rebuild communities hit by the conflict.

The "agreement fails to fulfil the rights of those who suffered some of the worst atrocities committed during the Colombian armed conflict and opens the door to perpetuating the country's cycles of impunity," said Jose Miguel Vivanco, the Americas director for Human Rights Watch

Santos' plebiscite is not without risks. Given Colombian antipathy to the rebels, Britain's stunning vote to leave the European Union is a cautionary tale.

Colombia's opposition is likely to try to convert the vote into a referendum on Santos, whose approval rating plummeted to 21 per cent in May, according to a Gallup poll. That is the lowest since he took office in 2010.

Low voter turnout is also a concern because a minimum of 13 per cent of the registered voters, or about 4.4 million voters, must vote in favour for the accord to be ratified.

"We think we've done the best possible job, but it's the Colombians who will judge us," chief government negotiator Humberto de la Calle said. "We have to wait for the citizens' verdict."

After the agreement is signed - the date is still unknown - the FARC will begin mobilizing its troops to 31 zones scattered across Colombia, and 90 days later they are supposed to begin handing their weapons over to UN-sponsored monitors.

Over the 13 months since the FARC declared a unilateral cease-fire and the government reciprocated with an unofficial truce, violence has fallen to the lowest level since the movement was created 52 years ago by outlaw peasant groups joined by communist activists.

But analysts are concerned that as the rebels integrate into Colombian society, well-organized criminal gangs will fill the void and fight among themselves for control of the country's lucrative cocaine trade, which kept the FARC well-armed much longer than other Latin American insurgencies.

The much-smaller National Liberation Army also remains active, although it's pursuing a peace deal of its own.

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Associated Press writers Andrea Rodriguez in Havana and Cesar Garcia and Libardo Cardona in Bogota contributed to this report.