Colombian President Juan Manuel Santos and the leader of the Farc rebel group have set a six-month deadline to sign a peace deal.

President Santos and the rebel leader known as Timochenko shook hands in Cuba, where the two sides have been holding peace talks since 2012.

On Wednesday, they reached agreement on how to punish human rights abuses committed during the conflict.

The issue had been seen as one of the biggest hurdles on the road to peace.

"We're not going to fail! This is the chance for peace!," President Santos said.

"On 23 March 2016 we will be bidding farewell to the longest-running conflict in the Americas," he added.

"Let's join efforts to achieve peace," Farc leader Timochenko later posted on the rebels’ Twitter feed.

The guerrilla group also agreed to surrender its weapons within 60 days of a final accord being signed.

US Secretary of State John Kerry hailed the deal as "historic progress" and expressed his "deep appreciation to Pope Francis for his moral leadership and the Vatican's good offices in the quest for peace".

During his visit to Cuba, Pope Francis had alluded to previous failed peace negotiations between the two sides and warned them that "we can't allow another failure on the road to peace and reconciliation".