Pope Francis, saying he wanted to be a servant of society's neediest presided at a Holy Thursday ceremony where he washed and kissed the feet of 12 men and women in a Rome prison housing many hardened criminals.

For the third consecutive year, Pope Francis did not hold the traditional service in a basilica, going instead to people on the margins of society.

His predecessors had only included men in the service, which commemorates Jesus' gesture of humility towards his apostles on the night before he died, but Pope Francis included women.

He knelt before the six male and six female inmates, poured water over each prisoner's right foot, dried it with a cloth and kissed it. One of the inmates, an African woman with tears in her eyes, held her child on her lap and the pope washed the child's foot.

Pope Francis' decision to include women and sometimes non-Christians - a Muslim woman was in the group two years ago at a juvenile prison - has upset conservative Catholics.

The 12 inmates selected to represent the 2,100 prisoners were from Italy, Nigeria, Congo, Ecuador and Brazil.

The four-day period that started on Thursday is the busiest in the liturgical calendar for the leader of the world's 1.2 billion Roman Catholics.

He presides at two Good Friday services, including a Via Crucis (Way of the Cross) procession around the Colosseum today.

After celebrating Easter Eve and Easter Day Masses, he delivers his twice-yearly "Urbi et Orbi" (to the city and the world) message on Sunday.