Leftist FARC guerrillas resumed peace talks with the Colombian government Monday in Cuba, after a year-end break.

The Bogota government and the Revolutionary Armed Forces of Colombia have been negotiating for more than two years in Havana to bring an end to the 50-year insurgency, but key issues remain unresolved, including disarmament and how any agreement should be ratified.

"We resumed the talks, and are hoping to continue to seek an agreement in the terms known by the people of Colombia and the whole world," said a statement from the guerrillas read to the press by commander Joaquin Gomez.

Gomez criticized an initiative launched by President Juan Manuel Santos in 2013 that would put any peace accord to a national referendum.

"Everything has its time and place, which does not give space to false solutions like referendums with electoral flavors and ambitions beyond what was already agreed," said Gomez.

The FARC also opposes a "legal framework" advanced by Santos as a way of dealing with the question of how to hold demobilized guerrillas legally accountable for actions during the conflict.

In August, the Colombian Constitutional Court upheld a "legal framework" that would allow the rebels to get involved in politics once they lay down their arms, with the exception of those most responsible for crimes against humanity or genocide.

The government delegation led by Humberto de la Calle made no statements to the press as the two sides resumed negotiations after taking a break for a month and a half, during which the FARC declared a unilateral ceasefire.

But over the weekend, Santos defended the legal framework, saying it "allows flexibility in judicial matters in order to achieve peace."

"Reconciling our two directly antagonistic positions is the great challenge that lies ahead at the negotiating table. I hope that by being creative and with political will on both sides, we will find that balance," he added in a speech in the southwestern town of Guapi.

Peace negotiations began in November 2012 and so far the two sides have agreed on three of the six points of the agenda to end a conflict estimated to have claimed the lives of more than 220,000 people over half a century.