Pope Francis talked of peace and reconciliation as he sported an impressive black eye on his last day of his tour of Colombia.

Despite his jokes saying 'I was punched', the pontiff's injury came not from violence but from bumping his head while on his popemobile in the port city of Cartagena.

The vehicle used to transport Francis among crowds came to an abrupt stop amid the throngs of people and the pope, who only has a hip-high bar to hold onto, lost his balance and bruised his cheekbone and cutting his left eyebrow.

Despite a blood stained white cassock, Pope Francis continued on the last day of his visit with hundreds of thousands gathering to hear him preach.

'The pope is fine. He injured his left cheekbone and eyelid,' spokesman Greg Burke confirmed.

Shortly before praying he used the town's famous Saint Peter Claver, a Spanish priest who ministered to slaves in the 1600s, to speak about modern slavery and human trafficking.

'If Colombia wants a stable and lasting peace, it must urgently take a step in this direction, which is that of the common good, of equity, of justice, of respect for human nature and its demands,' he told the violence strewn nation

'Only if we help to untie the knots of violence, will we unravel the complex threads of disagreements,' he said.

The pope dedicated the trip to 'reconciliation and peace' before he left Rome five days for a country that has been torn by armed conflict since 1964, and it is weighed down by drug-trafficking related to cocaine production.

As America Magazine pointed out, Colombia has suffered from an internal conflict that began decades ago when two guerrilla movements—the FARC (Fuerzas Armadas Revolucionarios de Colombia) and the Marxist-led ELN (Ejército de Liberación Nacional)—began fighting the government for land rights and to protect rural communities.

But Pope Francis used his trip to urge Colombians to eschew violence as he prayed before St Claver's relics.

'Here in Colombia and in the world, millions of people are still being sold as slaves; they either beg for some expressions of humanity, moments of tenderness, or they flee by sea or land because they have lost everything, primarily their dignity and their rights,' he said.

'From this city, known as the seat of human rights, I appeal for the rejection of all violence in political life and for a solution to the current grave crisis, which affects everyone, particularly the poorest and most disadvantaged of society.'

Additional reporting by Reuters.