The Colombian government and the left-wing Farc rebel movement have both asked the UN for a mission to oversee the end of their decades-long conflict.
Negotiators for the two sides at peace talks in Cuba said they would ask the UN to send a 12-month mission to oversee any ceasefire.
The UN has yet to agree to the proposal. The two sides have been holding peace talks for three years.
Both sides say they hope to reach a final peace deal by March 2016.
The BBC’s Colombia correspondent Natalio Cosoy says the mechanism would only start to work once a final deal is agreed.
“We have decided to ask the UN Security Council to create (a mission) of unarmed observers for a period of 12 months,” the two sides said in a joint statement at peace talks in Havana on Tuesday.
They said the mission would guarantee that any ceasefire and disarmament would be genuine and permanent, calling the announcement a “transcendental” moment, according to the Associated Press.
Correspondents say the fact that the two sides agreed to make the request jointly has raised hopes that they are close to signing a final peace deal.
An estimated 220,000 people have been killed in the fighting between Farc and the Colombian military, which began in 1964. It is the longest-running armed conflict in the Western Hemisphere.
Farc and the government negotiators started official peace talks in the Cuban capital, Havana, in November 2012.
Since then, they have reached agreement on the political participation of the rebels, land rights, drug trafficking, and transitional justice.
However it is unclear whether a final deal can be reached by the 23 March deadline that negotiators set last year.