VATICAN CITY - Pope Benedict XVI demanded urgent action by the European Union and African nations on Sunday to stop the trafficking in migrants, saying the global economic crisis was driving more people to make the perilous voyage.

Benedict recalled the drowning last week of more than 200 Europe-bound migrants whose overcrowded boat capsized in the stormy waters off Libya.

"We cannot resign ourselves to such tragedies, which unfortunately have been repeating themselves for some time," Benedict said during his Palm Sunday Mass.

"The scope of the problem requires urgent strategies co-ordinated by the European Union and African countries, as well as the adoption of adequate humanitarian measures, to prevent these migrants from going to unscrupulous traffickers," Benedict said.

Having returned recently from his first trip to Africa, Benedict said the problem was getting worse because of the global economic crisis and would only end once African nations, with international help, "free themselves from misery and war."

Benedict has been speaking out about the plight of the poor in the global downturn, particularly following his visit last month to Cameroon and Angola. He has been working on an encyclical on globalization and the poor, and said recently he is refining it because of the economic downturn. An encyclical is the most authoritative document a pope can issue.

Benedict's message came at the end of his open-air Palm Sunday Mass, in which he also warned the faithful that life isn't worth living without sacrifice.

"Whoever promises you a life without having to give of yourself is deceiving you," Benedict said. "A good life doesn't exist without sacrifice."

Wearing intricate red and gold brocaded vestments and clutching a braided palm frond, Benedict processed through St. Peter's Square at the start of the service. Many of the thousands of tourists and faithful gathered under brilliant blue skies also clutched palm fronds or olive branches.

Palm Sunday commemorates Jesus Christ's triumphant entry into Jerusalem, when he was greeted by the faithful who waved palms and olive branches in a sign of joy and peace.

The service marks the start of the Catholic Church's solemn Holy Week, which includes the Good Friday re-enactment of Christ's crucifixion and death and a Mass marking his resurrection on Easter Sunday.