Colombia's high commissioner for peace is urging the U.N. political mission that will monitor and verify a future cease-fire to fully deploy in the next three or four weeks — before the government and leftist rebels reach a final peace accord.

Secretary-General Ban Ki-moon said in a report to the Security Council circulated Friday that the mission will operate in 140 locations and require about 450 observers and some civilians.

Sergio Jaramillo told reporters earlier Friday that the mission needs to deploy as quickly as possible so that when negotiators in Havana, Cuba, reach agreement the U.N. will be on the ground and give "guarantees to Colombians that they can vote freely."

Last month, Colombia's top court approved the government's plans to hold a plebiscite on the peace deal.