Christians around the world have held Palm Sunday services in the week leading to Easter.

In Rome Pope Francis led a Palm Sunday mass before more than 100,000 people some of whom waved palm and olive branches when the pontiff arrived at St. Peter's Square in a white jeep.

In California Pastor Rick Warren of the Saddleback Church noted that Easter is one of the two biggest weekends for most churches in terms of attendance.

"I see this as a great opportunity for evangelism to begin and for a relationship to start between your church and all of the visitors who come that Sunday," Warren said on pastors.com.

"At the same time, it's important not to 'put all your eggs in the Easter basket.' What I mean is, Easter is a great starting point for evangelism, but it's not the finish line, at least not for a purpose driven church. In our culture, it usually takes multiple exposures to the Gospel for someone to make a decision to follow Jesus."

Easter Sunday is along with Christmas the most holy feast for Christians that celebrates the resurrection of Jesus on the third day after his crucifixion at Calvary as described in the Bible's New Testament.

This year Easter will be celebrated on April 20 for both Western churches, according to the Gregorian calendar and by Eastern Oriental churches that follow the Julian calendar.

In an impromptu homily Francis spoke of the last two days of Jesus' life and of his betrayal by the apostle Judas that led to his arrest, beating, trial and crucifixion.

Palm Sunday is a celebration of Jesus' entry into Jerusalem before his humbling journey to the cross and it marks the start of Holy Week in the Christian calendar.

Maundy Thursday remembers the Last Supper prior to Jesus' arrest, and at St. Peter's this is commemorated in mass when the priest washes the feet of 12 volunteers, signifying Jesus' 12 apostles.

Good Friday is the remembrance of Jesus' sacrificial offer of his life for the sins of man through the crucifixion according to Christian belief.

The Pope on Sunday asked those present to think hard about who they resembled more, those who helped Jesus or those who condemned him, betrayed him or were indifferent to his fate.

He said: "Has my life fallen asleep?''

"Am I like Pontius Pilate, who, when he sees the situation is difficult, washes my hands?''

"Where is my heart? Who among these people am I like? This question will remain with us all week," he said.

A year ago Francis held the Palm Sunday service at a youth jail, where he washed and kissed the feet of women and Muslim inmates.

During Sunday's mass he walked with a pastoral cross carved from olive wood by the inmates of another Italian jail.