MEDELLIN, Colombia (AFP) - Nearly 1.3 million worshippers flocked to a mass by Pope Francis on Saturday (Sept 9) in the Colombian city known as the stronghold of the late drug lord Pablo Escobar.

On the third stop in a four-city Colombian tour, Francis held an open-air mass in Medellin, home of the cocaine cartel depicted in the hit Netflix series Narcos.

The Argentine Pope, 80, has spent the trip pleading for reconciliation following a peace agreement that ended Colombia's half-century civil war. Francis met with victims and ex-fighters.

In Medellin, he also urged the Church to get out its comfort zone in order to confront challenges such as Colombia's peace process.

"The Church is 'shaken' by the Spirit in order to lay aside comforts and attachments," he said in his homily.

"We should not be afraid of renewal. The Church always needs renewal... Renewal entails sacrifice and courage."

Medellin is the political stronghold of former president Alvaro Uribe, the leading opponent of a recent peace accord between the government and the Farc rebel group.

Organisers of the mass said 1,293,000 people were in attendance.

"The pope has come to Medellin to talk about vocation," said Marcela Hincapie, 40, who spent all night waiting to take her place at the service.

"I would like the church to help the young people, drug addicts, hitmen and those who get involved in drug trafficking," Hincapie told AFP.

Francis supported the contested peace process that has led to Colombia's biggest rebel group, the Farc, disarming and turning into a political party.

The government pushed the Farc accord through congress despite resistance from critics who said the rebels were getting off too lightly with amnesties and alternative sentences.