A white dove sits in front of Pope John Paul II as a  Swiss guard stands behind him in St. Peter's  Square at the Vatican Thursday, April 10, 2003,  during a special meeting organized in preparation  of the next World Youth Day that will be held in  2005 in Cologne, Germany. The pontiff urged  youths to become "promoters of the culture of  peace" in a world torn by terrorism and war.  (AP Photo/Massimo Sambucetti)

VATICAN CITY - Pope John Paul II celebrated Palm Sunday Mass in St. Peter's Square before tens of thousands of young people, urging "brotherly solidarity" with their peers suffering during the conflicts in Iraq, the Holy Land and elsewhere in the world. Many waved palm fronds and olive branches as John Paul was driven to the canopied altar atop the steps of St. Peter's Basilica.  The Mass, attended by a crowd of at least 30,000 people, marked the start of a week of commemorations leading up to Easter, when Christians celebrate the resurrection of Christ.  For the 82-year-old pope, Holy Week this year is tinged by the U.S.-led war in Iraq. The pope was a staunch opponent of the war, and has frequently expressed his concern for the victims.  Palm Sunday is also the church's World Youth Day in years the event is not held outside of Rome.

Addressing himself to the young people in the square, John Paul said: "And how can you not express brotherly solidarity with your contemporaries tried by war and violence in Iraq, the Holy Land and other regions of the world?" 

"Peace is a gift of Christ," the pope said. 

Palm Sunday marks Christ's entry into Jerusalem before his arrest and crucifixion, when the people of the city strewed palm branches in his path. Cardinals in red robes and carrying palm branches led a procession into the square as John Paul arrived for the Mass. 

The pope called Jerusalem "the city of peace, which through the centuries has known violence, war and deportation." 

"In some way, the city of Jerusalem can be considered the symbol of humanity, especially in the dramatic beginning of the Third Millennium which we are living," John Paul said. 

The Mass was attended by delegations from Canada, where World Youth Day was held last July in Toronto, and Germany, where it is scheduled to be held in Cologne in 2005. The Canadians were handing over the 13-foot wooden World Youth Day Cross to the Germans. 

Later in the week, the pope is to preside over a Holy Thursday service, a Good Friday evening procession at the Colosseum and a vigil service on Saturday night in the basilica. He will deliver his traditional Easter message Sunday.