Colombia's government and the Revolutionary Armed Forces of Colombia (Farc) rebels have announced a revised peace deal to end 52 years of armed conflict, after voters rejected a prior peace accord in a referendum.

"We have reached a new final agreement to end the armed conflict, which incorporates changes, clarifications and some new contributions from various social groups, which we have gone through one by one," said a joint statement read out by diplomats from Cuba and Norway, the peace process guarantors.

"Building a stable, lasting peace must be the shared commitment of all Colombians, and one that helps polarisation be overcome while including all social and political voices," the statement added.

Colombia's President Juan Manuel Santos stressed that the new peace deal "is a better agreement."

"We made adjustments, tweaks and changes in 56 of the 57 issues that were addressed," Mr Santos said, so "we can build a deeper and broader peace."

The modified agreement leaves intact the accord's major tenets, including Marxist group Farc laying down its arms and becoming a political party.

However, it includes a number of "innovations" to several of the key points in the original peace deal, according to the government's lead negotiator Humberto De la Calle.

In Bolivar Square at the heart of historic Bogota, dozens of people celebrated the news with white balloons and Colombian flags.

The new accord was fine-tuned after the groups that opposed the original deal submitted proposed changes as starting points for negotiations.

"The tweaks and clarifications we have made do not undermine the issues we agreed on, which shaped the first peace deal," Mr De la Calle said.

Mr Santos acknowledged that a suggestion seeking to bar rebel leaders involved in serious crimes from elections was not part of the re-worked peace deal.

He also hinted that the new accord would maintain the provision that Farc rebels could avoid prison time by confessing and carrying out acts of reparation to victims.

But he added that there would be specifications concerning the "effective restriction of their freedom."

The agreement also states that foreign magistrates will not be allowed on special tribunals to hear cases about those involved in the conflict.

An upbeat chief rebel negotiator Ivan Marquez said "the only thing the new accord needs now is to be put into effect."

At the moment, neither side has made any mention of the new peace deal being put before a new referendum vote.

The United States hailed the agreement, and pledged continuing US support in implementing a peace under which the guerrillas would demobilize and become a political party.

US Secretary of State John Kerry said in a statement that the new accord "constitutes an important step forward on Colombia's path to a just and durable peace."

Farc and Santos' government had been meeting since 22 October to try to rescue a peace deal that has taken four years to negotiate.

In an 2 October referendum, voters unexpectedly rejected the peace agreement, deeming it too soft on the country's largest rebel group.

The development was a blow to Santos, who won the Nobel Peace Prize last month for his efforts to bring "total peace" to Colombia.

Meanwhile, talks with the smaller ELN (National Liberation Army) have been on hold over government demands that it first free all hostages.

Founded in 1964, the Farc and the ELN are the last two leftist guerrilla groups involved in a messy, multi-sided conflict that has killed more than 260,000 people, left seven million displaced and 45,000 more people missing.

Santos's government had been due to open peace talks with the ELN, Colombia's second-largest rebel group on 27 October.

But he called them off when the rebels failed to release ex-congressman Odin Sanchez, which he had set as a precondition.