VATICAN CITY - Pope Francis looked well on Thursday as he began four intense days of events leading to Easter.

He also renewed his own ordination vow on the day the Roman Catholic Church marks the founding of the priesthood by Jesus Christ the night before his Crucifixion.

Pope Francis, who recently curtailed his speaking engagements because of fatigue linked to bouts of bronchitis and influenza, read a long homily during a Holy Thursday Mass of the Chrism in St Peter's Basilica.

He urged priests to be compassionate, admit when they have "strayed from the path of holiness" and avoid duplicity, dishonesty and hypocrisy.

During the service, the 87-year-old pontiff renewed his vows along with thousands of priests in the basilica and blessed oils that will be used in Church sacraments.

Holy Thursday marks the day of Jesus' Last Supper with his Apostles the night before he died.

On Thursday afternoon, the Pope was due to preside at a traditional foot-washing ritual in the women's section of a Rome prison.

Pope Francis is the first pope to hold the foot-washing ceremony outside churches, usually in prisons, homes for the elderly or hospices, continuing a practice he began when he was Archbishop of Buenos Aires.

He is also the first pope to include women and non-Christians in the service. The ceremony echoes Jesus' gesture of humility toward his Apostles on the night before he died.

On Good Friday - the day Christians mark Jesus' Crucifixion - Pope Francis is due to preside at a Passion of the Lord service in St Peter's Basilica, and then attend a traditional evening Via Crucis or Way of the Cross procession at Rome's Colosseum.

He will preside at an Easter Vigil service on Saturday, and then on Sunday read his twice-annual Urbi et Orbi message and blessing from the central balcony of St Peter's to tens of thousands of people in the square below. Urbi et Orbi means to the city and world in Latin. REUTERS