Colombia and the FARC have "considerable differences" about what kind of justice should be meted out to rebels who lay down their arms as part of a peace agreement, a top negotiator acknowledged Monday.

"These issues are very complex," said Humberto la Calle, Bogota's chief negotiator in talks with the Marxist guerrilla group.

"In the matter of transitional justice, as might be expected, we are still facing considerable differences," la Calle said.

The talks, which have been held in Cuba since November 2012, aim to end Latin America's oldest conflict, which has claimed more than 220,000 lives over the past 50 years.

The delegations have been holding technical discussions in recent days "to examine the general panorama for the next stages" of the negotiations, de la Calle said on Colombian television. A new round of negotiations is scheduled to begin February 2.

Besides reparations for victims and a cease-fire, negotiators are expected to take up the question of legal status of former guerrillas. Opponents of the peace process have accused the government of offering to let them walk free without punishment.

"Colombia must adapt to international and national standards, notably where international crimes are concerned," said de la Calle, adding however that there was still "room for penal alternatives."

During a previous peace process in the early 2000s with right-wing paramilitary groups blamed for massacres of civilians, Colombian authorities offered members of those groups reduced sentences in return for confessions.

But an overwhelming majority of Colombians, 89 percent, oppose dispensing with prison sentences for the guerrillas, according to a poll made public in October by Radio Caracol.

The FARC, formed in 1964, has an estimated 8,000 fighters, mainly deployed in rural areas.