An historic ceasefire came into effect in Colombia on Monday, ending a 52-year war between FARC rebels and the government and taking a major step toward ending a conflict that has claimed more than 250,000 lives.

The full ceasefire ordered by President Juan Manuel Santos and the head of the Revolutionary Armed Forces of Colombia (FARC), Timoleon Jimenez, began at midnight (0500 GMT).

"This August 29 a new phase of history begins for Colombia. We silenced the guns. THE WAR WITH THE FARC IS OVER!" Santos wrote on Twitter one minute later.

A message from the official FARC account at the same time was more restrained: "From this moment on the bilateral and definitive ceasefire begins."

The government's chief peace negotiator, Humberto de la Calle, grew visibly emotional at a press conference describing how church bells and sirens had rung out in some of the areas hardest hit by the conflict.

"It was a war against the civilian population, 80 percent of those who died were civilians," he said.

Sergio Jaramillo, the country's high commissioner for peace, added: "A lot of human lives are going to be saved with this giant step we are taking today."

"The morning of peace has dawned," tweeted the FARC's chief negotiator, Ivan Marquez.

The ceasefire is the first in which both sides are committed to a definite end to the fighting.

"The ceasefire is really one more seal on the end of the conflict," said Carlos Alfonso Velazquez, a security expert at the University of La Sabana.

- Peace referendum -

The conflict began in 1964 with the launch of the FARC, a Marxist guerrilla group born out of a peasant uprising. It has left 260,000 dead, 45,000 missing and 6.9 million uprooted from their homes.

To end the war with the FARC for good, Colombians must now vote in an October 2 referendum on the peace accord hammered out in nearly four years of talks in Cuba.

Santos said the exact question that will be put to voters in the referendum would be announced "in the coming days".

"We are on the verge of perhaps the most important political decision of our lives," he said in a speech on Saturday.

Colombia's Congress on Monday approved the plan to call a referendum.

Opinion polls show Colombians are divided ahead of the vote.

Santos's top rival, former president Alvaro Uribe, is leading a campaign to vote "no" to the peace deal.

"This is not an agreement: this is the state submitting to the proposals of the narco-terrorist group FARC," Uribe said at a university forum.

He has said a special justice system envisaged for crimes committed during the conflict would give FARC fighters impunity.

Opponents question the FARC's commitment to peace.

"I don't think we can believe them," said Felipe Giraldo, a 25-year-old unemployed man in Bogota.

Others have a high personal stake in the vote.

Adelaida Bermudez, 50, hopes it will bring home her daughter, who joined the FARC nine years ago.

"I hope we'll have peace... so the children come home," she said in Gaitania, in the central region where the FARC was born.

- Demobilization -

Santos and Jimenez are due to sign the peace agreement sometime between September 20 and 30 -- possibly at the United Nations General Assembly in New York, said Foreign Minister Maria Angela Holguin.

The end of hostilities will be followed by a six-month demobilization process.

Starting Monday, the FARC's estimated 7,500 fighters are to go to collection points to surrender their weapons under UN supervision.

Guerrillas who refuse to demobilize and disarm "will be pursued with all the strength of the state forces," Santos told El Espectador newspaper.

Before the demobilization, the FARC will convene its leaders and troops one last time before transforming into "a legal political movement," according to a statement published on Saturday.

- Reconciliation -

The territorial and ideological conflict has drawn in various left- and right-wing armed groups and gangs.

Efforts to launch peace talks with a smaller rebel group, the National Liberation Army (ELN), have yet to bear fruit.

But with the FARC ordering a ceasefire, the conflict appears to be reaching an end.

"We wish to express our clear and definite will for reconciliation," said Jimenez, known by the nom de guerre Timochenko, in Havana.

"Today more than ever we regret that so much death and pain has been caused by the war. Today more than ever we wish to embrace (the military and police) as compatriots and start to work together for a new Colombia."

Santos and Timochenko: Colombia foes turn peacemakers
Bogota (AFP) Aug 29, 2016 - A conservative politician from a rich family and a rural Marxist guerrilla are the lead players in the Colombian peace process, which culminated in a ceasefire Monday after five decades of conflict.

Here are short profiles of President Juan Manuel Santos and FARC rebel leader "Timochenko", former foes now on the verge of ending a conflict that has claimed more than 260,000 lives.

- Santos: fighter for peace -

Santos, 65, led a major offensive against the FARC as defense minister from 2006 to 2009.

After becoming president in 2010, he shifted tack and negotiated for peace.

"He made war as a means to achieve peace," said his brother-in-law and adviser, Mauricio Rodriguez.

"He weakened the FARC to make them sit at the negotiating table."

Santos comes from a wealthy, powerful family.

His great uncle was also head of state.

He was educated at the London School of Economics and previously served in various ministerial posts.

- Timochenko: convict negotiator -

The bearded, bespectacled FARC leader's real name is Rodrigo Londono, but he is better known by his noms de guerre Timoleon Jimenez and Timochenko.

He was born in a coffee-growing region and studied medicine in the Soviet Union and Cuba.

Timochenko, 57, is renowned as a strategist and former intelligence chief in the Revolutionary Armed Forces of Colombia (FARC).

He has been convicted in absentia for various attacks for which he has been sentenced to more than 150 years in jail.

He took over as FARC leader in 2011 after his predecessor, Alfonso Cano, was killed by the army.

The following year, he wrote to Santos proposing fresh peace negotiations after efforts by previous leaders had failed.

He agreed to one of Santos's key conditions, pledging to end kidnappings by the group.

"He is one of the most well-liked guys in the FARC," analyst Ariel Avila of Colombia's Peace and Reconciliation Foundation told AFP.

"He is the man who will go down in history for bringing the FARC into the peace process."