The act of foot-washing at the Mass of the Lord's Supper on Holy Thursday is part of the Christian tradition that mirrors Jesus' washing of his disciples' feet.
The girls whose feet Francis washed -- in another move away from custom -- were an Italian and an Eastern European, according to the Vatican.
The Vatican Press Office responded Friday to "questions and concerns" related to the pope's washing the young offenders' feet, especially those of two females, calling it a "simple and spontaneous gesture of love, affection, forgiveness and mercy."
"When Jesus washed the feet of those who were with him on the first Holy Thursday, he desired to teach all a lesson about the meaning of service, using a gesture that included all members of the community," the office said in a statement. "... To have excluded the young women from the ritual washing of feet ... would have detracted our attention from the essence of the Holy Thursday gospel, and the very beautiful and simple gesture of a father who desired to embrace those who were on the fringes of society."