Pope Benedict XVI blasted Europeans for being selfish and not having enough children, in a sermon at the 850-year-old pilgrimage site of Mariazell in Austria.

"Europe has become child-poor. We want everything for ourselves and place little trust in the future," the Pope told a crowd of faithful from his canopied area at an open-air, afternoon mass that took place under heavy rain.

But Pope Benedict held out hope, saying: "The earth will be deprived of a future only when the forces of the human heart and of reason illuminated by the heart are extinguished . . . Where God is, there is the future."

Meanwhile, in evening prayers at Mariazell the traditionalist Pope defended chastity for religious orders as a way for them to become "men and women of hope."

Celibacy is not "individualism or a life of isolation" for priests, nuns and other religious orders but "unreservedly" serving God and having "deep relationships ... which they accept as a gift."

The Austrian Church has been wracked by several sex scandals involving priests and in an open letter to the pope the liberal Austrian movement Wir sind Kirche ("We are the Church") has called for the end of celibacy.

Despite the bad weather that has dogged the visit so far, thousands stood in the rain at Mariazell packed behind crowd barriers, with many wearing yellow raincoats and some waving blue scarves, the traditional colour of Jesus's mother Mary.

On Friday, the pontiff said he intended his pilgrimage "to be a journey made in the company of all the pilgrims of our time."

He said Mariazell "symbolises an openness which... transcends physical and national frontiers."

The main pilgrimage site in the Danube region, some 110 kilometres south-west of Vienna, has a basilica was founded by Benedictine monks.

The site, which is dedicated to the Virgin Mary and celebrates its 850th anniversary this year, welcomes around a million pilgrims every year from Austria, neighbouring Hungary, Czech Republic, Slovakia and Slovenia as well as Poland, Croatia and Bosnia-Herzegovina.