The government negotiating team, announced by Santos on Wednesday, will include the two men who led the preliminary talks, national security adviser Sergio Jaramillio and former peace commissioner Frank Pearl.
Also named to it are former Interior Minister Humberto de la Calle, widely respected former national police director Oscar Naranjo, former armed forces chief Jorge Enrique Mora and Luis Carlos Villegas, president of Colombia's main business group.
After taking office in mid-2010, the 61-year-old Santos said the FARC, badly weakened by a decade-long US-fortified military buildup, would need to seriously curtail hostilities if its peace overtures were to be taken seriously.
As a condition for launching the talks, the FARC agreed to halt ransom kidnappings, the senior official said. It also agreed for the first time, the official said, to disarm at the signing of a peace agreement. Demobilized rebels would then take part in everything from destroying coca crops to launching political movements.
The talks will now proceed, outside Colombia, without any halt in combat and without any safe havens.
The Andean nation's internal conflict, which has claimed tens of thousands of lives, has not persisted a half-century by accident. It is maddeningly complex in a country with one of the world's widest gaps between rich and poor and the second largest internally displaced population after Sudan.
Potential spoilers to a peace deal abound, particularly to the agrarian reform and rural development that Santos, a social progressive, says would be part of a successful deal.
Resistance can be expected from wealthy ranchers and plantation owners allied with Alvaro Uribe, who as president in 2002-2010 waged war without quarter against the FARC while making peace with far-right militias that did most of the dirty war killing.