VATICAN CITY - Pope Francis presided over a Good Friday service in St Peter's Basilica ahead of a night-time procession at Rome's Colosseum for the most somber day in the Christian calendar, marking Jesus' death by crucifixion.

The pontiff, the Vatican said, will not attend a Good Friday procession at Rome's Colosseum to protect his health ahead of other Easter week engagements.

The 87-year-old pontiff, who is hobbled by mobility and respiratory issues but looked fitter this week, arrived in St Peter's with a wheelchair as he joined cardinals and bishops for Good Friday's Passion of the Lord service.

Good Friday leads on Sunday to Easter, the most important and joyous date in the Church's liturgical calendar - commemorating the day Christians believe Jesus rose from the dead.

Francis will preside at an Easter Vigil service on Saturday and then on Sunday celebrate Easter Mass and read his twice-annual "Urbi et Orbi" (to the city and world) message and blessing from the central balcony of St. Peter's.

In previous years, Francis would start it prostrating himself on the marble floor of the basilica, but his physical condition no longer allows him to do so. Instead, he prayed silently in front of the altar from his wheelchair.

The Passion of the Lord features chants in Latin that recount events from Jesus' arrest to his burial, and is one of the few services where the pope does not deliver a homily, leaving it to the preacher of the papal household.

Later on Friday, Francis was set to preside over the "Via Crucis" procession at the Colosseum, in which participants walk around the ancient Roman arena holding a cross, re-enacting Jesus' last hours and stopping to pray and hear meditations.

Francis personally wrote this year's meditations, a first in his 11-year papacy. They included praises for meekness and forgiveness in response to acts of evil, and prayers for persecuted Christians and war victims.

The pope, who has called for the Church to become less male-dominated, also hailed the women who helped Jesus while he carried the cross, and pleaded for "those (women) who in our own day are exploited and endure injustice and indignity".

In another sign of his focus on women, Francis on Thursday performed the foot-washing ritual, which recalls Jesus' gesture of humility to his apostles at the Last Supper, in a women's prison in Rome. — Reuters