UNITED NATIONS — The Security Council on Tuesday approved the deployment of a U.N. political mission to monitor a cease-fire between the government of Colombia and the Revolutionary Armed Forces of Colombia, or FARC.

The resolution unanimously approved authorizes a mission made up of 450 observers and a number of civilians to be deployed in 40 widely dispersed locations to oversee the laying down of arms by the FARC and other aspects of the agreement.

Diplomats say the mission should be in place when the two parties sign a formal peace agreement on Sept. 26 in Cartagena and when the deal goes to a national referendum on Oct. 2.

On June 23, Colombian President Juan Manuel Santos and FARC rebels signed a cease-fire and rebel disarmament deal that moved the country to the brink of ending the 52-year war.

“Colombians will have the opportunity to open the doors to a better future, with a stable and lasting peace which we have been able to construct with the support of the Security Council and the United Nations,” Colombia’s Ambassador Maria Emma Mejia said, thanking Britain for sponsoring the resolution authorizing the political mission.

British Ambassador Matthew Rycroft congratulated the Colombian government on reaching an agreement with FARC.

“It’s a nice change from the normal routine to have a positive issue to be dealing with in the Security Council and it’s also a pleasant change to be dealing with an issue where the government of that country has come to us, rather than us having to go to them. That is what the government of Colombia has done,” Rycroft said.

Decades of fighting between guerrillas, right-wing paramilitaries and the armed forces has left more than 220,000 Colombians dead, some 40,000 missing, and over 5 million driven from their homes.