Colombians hit their government with a shock defeat Sunday when they voted by a razor-thin majority to reject a historic peace accord with communist FARC rebels.

Voters narrowly defied the government's plan to put 52 years of bloody conflict behind them, reversing the trend of earlier opinion polls.

The 'No' camp won by about 57,000 votes which translated into a lead of less than half a percentage point, electoral authorities said.

President Juan Manuel Santos admitted defeat in the vote but vowed to continue peace efforts.

"The majority has said 'No,'" he said in a televised address. But he vowed: "I will not give in, and I will continue to seek peace to the last day of my term."

FARC chief Rodrigo Londono, alias Timoleon "Timochenko" Jimenez, also vowed the force was committed to continuing peace efforts.

"The FARC deeply deplores that the destructive power of those who sow hate has influenced opinion," he said in a speech in Havana, Cuba, where the accord was negotiated.

But it maintains "its willingness to use dialogue as the only weapon for building the future," he added.


Deadly conflict

Supporters of the accord had expected it to effectively end what is seen as the last major armed conflict in the Western hemisphere.

But Sunday evening's results were a crashing defeat for Santos and the accord that he signed with the Revolutionary Armed Forces of Colombia (FARC).

Media and online commentators compared the drama of the result to that of June's surprise "Brexit" vote for Britain to leave the European Union.

Colombians voted 50.21 percent to 49.78 percent against the accord, according to results published online with 99.9 percent of votes counted. Turnout was low at just over 37 percent.

Authorities earlier said heavy rain caused some disruption to voting as Hurricane Matthew passed over the Caribbean.


'No Plan B'

Sunday's result threw the country's future into uncertainty.

"Colombia is betting everything on this plebiscite, socially, economically and politically," said Jorge Restrepo, director of conflict analysis center CERAC, ahead of the results.

Santos's government had said it had no Plan B if voters rejected the accord.

The accord itself stipulated that the peace must be ratified by Colombians in a referendum. That move was endorsed by the courts.

Opinion surveys by pollsters Datexco and Ipsos Napoleon Franco, published on September 26, indicated the 'Yes" vote would win by a margin of around 20 percent.

The polls forecast a 'No' vote of only about 35 percent.

Opponents of the deal, drawn up at peace talks in Havana, Cuba, resented the concessions made to the FARC, which has carried out killings, kidnappings and extortion.

"Peace is exciting, but the Havana accords are disappointing," said the leader of the 'No' campaign, former president Alvaro Uribe.


'No' to rewarding 'criminals'

Many voters said they were sick of war.

"This is the path to leaving a better country for our children," Santos said.

But others said the accord was a reward to a group they see as terrorists.

"It is absurd to reward those criminals, drug traffickers and killers who have made the country a disaster for the past 50 years," said Jose Gomez, a retiree of 70, who voted 'No.'

"If you reward crime, what moral authority do you have to tell a thief not to steal your mobile phone?"


Disarmament, politics

The deal called for the 5,765 FARC rebels to disarm in six months and convert into a political group with seats in Colombia's Congress.

The accord covered justice and compensation for victims and an end to the cocaine production that has fueled the conflict.

The FARC launched its guerrilla war on the government in 1964, after a peasant uprising that was crushed by the army.

The ideological and territorial conflict drew in several leftist rebel groups, right-wing paramilitaries and drug gangs.

Colombian authorities estimate the conflict has left 260,000 people dead, 45,000 missing and nearly seven million displaced.