Pope Francis flies into Democratic Republic of Congo on Tuesday for a visit that will highlight the human cost of protracted conflict in the vast central African country.

The 86-year-old pontiff will celebrate Mass in the capital Kinshasa on Wednesday and meet victims of violence from the eastern part of the country, which is blighted by recurring fighting between rebels and government troops.

The last papal visit to Congo was by John Paul II in 1985, when it was still known as Zaire.

"We are fine-tuning our plans to greet the pope with joy, love and respect," said Catholic priest Victor Ntambwe, who has childhood memories of John Paul's visit and is now part of a Church committee organising the welcome for Francis.

"We have been stagnating here for 60 years. For the past 20, we have been under attack. The people are suffering and dying of hunger. We have too many widows and orphans," he said, adding that the pope would speak up for Congo on the world stage.

Congo has vast mineral wealth which has stoked conflict between militias, government troops and foreign invaders. It has also been affected by violence linked to the long and complex fallout from the 1994 genocide in neighbouring Rwanda.

An estimated 5.7 million people are internally displaced in Congo and 26 million face severe hunger, largely because of the impact of armed conflict, according to the United Nations.

First scheduled for last July, the pope's trip was postponed because he was suffering a flare-up of a chronic knee ailment. He had originally planned to visit the eastern city of Goma, but that stop was scrapped because of the violence.

Roman Catholics make up about half of Congo's population of 90 million and the Church plays a crucial role in running schools and health facilities.

Barriers were being erected along the pope's planned itinerary and security personnel were patrolling Kinshasa as the city awaited the pope's arrival, causing giant traffic jams and disrupting commutes and school drop-offs, residents said.

At the Martyrs' Stadium, a canopy overhanging a stage where the pope is scheduled to deliver a public address on Thursday collapsed during a storm on Sunday night. It was being repaired and authorities said it would be ready on time.

Francis will stay in Kinshasa until Friday morning, when he will fly to South Sudan, another country grappling with conflict and poverty.

In a first, he will be accompanied for that leg of his journey by the Archbishop of Canterbury, leader of the global Anglican Communion, and by the Church of Scotland Moderator.