Pontiff loses his balance and bumps his head while riding in the popemobile

Pope Francis celebrates Mass in the area of Contecar harbor in Cartagena, Colombia, after a minor accident in the popemobile. Photo / AP

Pope Francis, his eye bandaged and blackened after a minor accident in the popemobile, has left Colombia after appealling to the country to "untie the knots of violence" after a 50-year civil war.

His last day in the Andean country got off to a rocky start when he lost his balance and bumped his head while riding in the popemobile.

He bruised his cheekbone and cut his left eyebrow, blood staining his white cassock.

The Vatican said he received ice treatment and was fine.

A smiling Pope continued the trip wearing a bandage over his cut. "I was punched. I'm fine," the 80-year-old Pontiff joked afterwards, the bruises on his face clearly visible.

Pope Francis celebrates Mass in the area of Contecar harbor in Cartagena, Colombia. Photo / AP

At the end of the day, when he said Mass for about 500,000 people in the city's port area, the bruise had swollen and he had a black bag under his eye.

"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 said in a strong voice in the homily of the Mass, accompanied by Caribbean and salsa music.

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

The Pontiff left Colombia on an Avianca flight to Rome after watching a "cumbia" troupe perform traditional coastal singing and dancing with President Juan Manuel Santos and his wife, Maria Clemencia.

Cartagena, a top tourist destination famous for its colonial walled ramparts, was the home to Saint Peter Claver, a Spanish priest who ministered to slaves in Colombia in the 1600s, defying Spanish colonial masters who treated them as chattel.

The Pope also used the occasion to again decry modern slavery and human trafficking and defend the rights of immigrants.

- Reuters, AAP