FARC peace deal at risk as right closes in on Colombia presidency

Voters in Colombia went to the polls today to choose a new president in an election that has turned into a referendum on a landmark 2016 peace deal with FARC rebels, which conservative front-runner Ivan Duque wants to overhaul.

Offering a starkly different choice to voters is Duque's opponent, leftist former mayor and ex-guerrilla Gustavo Petro, who supports the deal.

"Let us continue to build a country at peace, a country of democracy, a country which we all hold dear and to which we all contribute," President Juan Manuel Santos, who will step down in August, said in urging citizens to cast their ballots.

His efforts to end the war with the Revolutionary Armed Forces of Colombia (FARC) brought him the Nobel Peace Prize, though he is leaving office with record unpopularity in a country of 49 million people.

The world's leading producer of cocaine, the Latin American country continues to battle armed groups vying for control of lucrative narco-trafficking routes in areas FARC once dominated.

Duque comfortably won the first round last month, having campaigned on a pledge to rewrite the agreement signed by Santos.

Vehemently opposed to the peace deal, the 41-year-old Duque says he would revise it in order to sentence guerrilla leaders guilty of serious crimes to "proportional penalties."