Santos, who won the Nobel Peace Prize for negotiating an end to the decades-old conflict with FARC rebels, spoke at a UN meeting on sustaining peace ahead of elections on May 27 to choose his successor.

"Today, drug trafficking continues to be the main threat to peace," said Santos, who is due to step down in August after serving eight years in office.

"If we want to protect peace in Colombia, in the region and in the world, we need to change the global strategy to overcome the drug problem."

The president stressed the need for "shared responsibility" between countries that produce and those that consume drugs and warned that without joint action, there will be "more arrests, more deaths and stronger drug mafias."

Colombia remains the world's leading supplier of cocaine, much of which is smuggled to the United States, the world's leading consumer of the drug.

On Monday, Colombia extradited to the United States a former right-wing paramilitary leader, Daniel Rendon Herrera, who is accused of having headed one of the country's largest drug cartels.

Santos, who signed the peace deal with Revolutionary Armed Forces of Colombia (FARC) in November 2016, said Colombia had succeeded to "make possible what was impossible."

"Ending armed conflicts, including the most complex and long-running ones, is possible," he said.

Colombia is reaping the benefits of peace. In 2017, homicides and rapes were at their lowest point in 42 years, Santos said.