Pope Francis has urged what he called a "haggered' Europe to reclaim global leadership after years of crisis and to take in migrants before the Mediterranean becomes a "vast cemetery".
The pope made the remarks during an address to the European Parliament and Council of Europe in Strasbourg where he demanded the continent craft a unified and fair immigration policy.
It was the first papal visit to the French city since John-Paul II in 1988, but where his predecessor came at the end of the Cold War, Pope Francis faces a more secular and eurosceptic continent riven by tensions.
"Europe seems to give the impression of being somewhat elderly and haggard, feeling less and less a protagonist in a world which frequently regards it with aloofness," the 77-year-old pope told the European parliament.
"We encounter a general impression of weariness and ageing, of a Europe which is now a 'grandmother', no longer fertile and vibrant."
The pope reserved some of his strongest language for calling for a "united response" to the plight of migrants fleeing the Middle East and Africa, more than 3,200 of whom have died trying to reach Europe this year alone.
He stressed the migrants needed acceptance and assistance, not self-interested policies that risk lives and fuel social conflict.
"We cannot allow the Mediterranean to become a vast cemetery!" he said.
The pope's comments follow gains by anti-EU and anti-immigration parties in May's European Parliament elections.
The leader of the world's 1.2 billion Roman Catholics received long standing ovations after his speech, which come amid a tide of growing economic despair, euroscepticism and anti-immigrant feeling across the continent.
The pope was also meeting briefly with new European Commission chief Jean-Claude Juncker, outgoing European Council President Herman Van Rompuy and President of the European Parliament Martin Schulz.
His visit has sparked protests in some quarters, including from a bare-breasted Femen rights group demonstrator who mounted the altar in Strasbourg cathedral on Monday, with critics angry over Schulz's decision to invite a religious leader to address a secular body.
The pope's speech repeated earlier warnings to Europe amid a rise in radicalisation, particularly among the disillusioned younger generation, and racism in countries hit hard by the economic crisis.
Source: Al Jazeera and agencies