Former UN secretary-general Kofi Annan arrives in Cuba on Thursday to help prod negotiators from the Colombian government and leftist guerrillas to clinch a peace agreement. The 2001 Nobel Peace Prize winner will meet with both delegations, after declaring in Colombia that any peace agreement must be just, and must meet the standards of the international community. "Transitional justice is an issue of concern and controversy in Colombia," Annan said Wednesday, referring to truth-seeking, reparations to victims and accountability for crimes. "However, I would like to emphasize that justice must fit the Colombian context -- while respecting international minimum standards. No one shoe fits all." Meanwhile, sources from both delegations told AFP that the new US special envoy for the Colombian peace process, Bernie Aronson, would travel to Cuba in the coming days to speak separately with each side. "He is not a guarantor of the peace process, he is not coming to mediate. He is coming to follow up on the issues. He will not be part of negotiations at the table," one of the sources said. Aronson will not attend closed-door negotiating sessions, unlike diplomats from so-called "guarantor" countries -- Cuba and Norway -- or "escort" countries -- Chile and Venezuela. Annan's meetings with the government and guerrilla delegations will take place at the Hotel Nacional de Cuba and not at the Convention Palace, the usual venue for the talks. Annan, who led the United Nations from 1997 to 2006, is expected to speak to the media on Friday about the visit. Colombia's civil conflict, the oldest in the region, has claimed more than 220,000 lives over the past half century and left 5.5 million people displaced.