SYDNEY--The Catholic Church will hold its next World Youth Day in the Spanish capital Madrid in 2011, Pope Benedict XVI said Sunday as he closed the festival in Sydney at a giant open-air mass.

"World Youth Day 2011 will take place in Madrid, Spain," the pope told hundreds of thousands of worshippers gathered at Sydney's Randwick racecourse for the celebration of Catholic youth.

"Until then, let us continue to pray for one another and let us joyfully bear witness to Christ before the world," he said.

The announcement sparked jubilation among the estimated 5,000 Spanish pilgrims who travelled to Australia for the event.

Church sources told AFP that Madrid was Benedict's personal choice as the next World Youth Day host. It marks a return to the Catholic Church's heartland after the event in Sydney, a largely secular city.

It will be the second time Spain has hosted the largest Christian gathering on earth after it staged the event in 1989 in the city of Santiago de Compostela. The event was last held in the German city of Cologne in 2005.

While Spain is a traditionally Catholic nation, the church feels it is particularly under threat from growing secularization.

The Spanish church is at loggerheads with the country's socialist government, which is seeking to review historically strong ties between church and state and move to a more secular system.

Relations between the church and Prime Minister Jose Luis Rodriguez Zapatero's government have deteriorated to such an extent that the Spanish Episcopal Conference advised Catholics against voting for the socialists at elections in March.

Zapatero's first term in office was marked by confrontation with the church over the government's liberal social reforms including gay marriage and easier divorce.

The socialist government argues the promotion of secular values is key to modernizing Spain, which has become more multicultural and undergone a liberal transformation in the three decades since the death of dictator General Francisco Franco.

The church remains influential in Spain, a country which is officially 80 percent Catholic but where only about 40 percent practise the religion.

The first World Youth Day was held in Rome in 1986 and is now held in an international host city every two to three years.