Alex Saab, 49, and his business partner Alvaro Pulido are accused in the United States of running a network that exploited food aid destined for Venezuela
Representatives of the opposition and the government of President Nicolas Maduro are taking part in talks in Mexico with mediation by Norway in a bid to lift the deadlock
These guerrilla dissidents have distanced themselves from Colombia's 2016 peace pact, which ended a half-century civil war and saw the FARC disarm the following year.
After the breakdown of the peace process, Duque demanded that Cuba extradite the rebels in its territory, which President Miguel Diaz-Canel's government opposed.
Maduro on Sunday presented the drug Carvativir, an oral solution he said was tested on patients in a Caracas hospital and a sports center used as an emergency medical facility.
It has gone through a period of nine months of study, experimentation, clinical application.