President Ivan Duque, who has unsuccessfully tried to change certain clauses in the agreement that saw 7,000 former guerrillas lay down arms, presented the request to Security Council ambassadors visiting the South American country.

"I've given the Security Council president the letter that confirms we would like the mission to accompany us for another year," he said in a statement to media at the foreign affairs ministry.

With UN support, the peace accord brought to an end the insurrection by the Revolutionary Armed Forces of Colombia and turned the Marxists into a political party called the Common Alternative Revolutionary Force, which uses the same FARC acronym.

While it hasn't ended violence in the country -- other left-wing rebels, right-wing paramilitaries and drug traffickers are still waging their battles -- it has helped to reduce it.

The right-wing Duque was elected last year with a promise to modify the peace accord, which he considers too lenient on ex-fighters guilty of serious crimes.

The FARC political party, meanwhile, has denounced delays in the application of the accord as well as a lack of legal guarantees and security for its members.

It has pointed to what it says are the murders of 140 former guerrillas, and 31 of their family members, since the agreement was signed.

The deal has also been weakened by the decision of some former guerrilla commanders to distance themselves from the accord, including two of FARC's chief negotiators, Ivan Marquez and Jesus Santrich.

UN Security Council President Gustavo Meza assured Duque of the international body's support.

"The Colombian peace process remains an example not just for Latin America but for the whole international community and in that sense we've reiterated to the president our commitment to keep supporting the future implementation" of the deal, the Peruvian said.

Eight million people were killed, disappeared or displaced during the 50-year conflict.