Pope Francis has called for a global economic system that puts people and not "an idol called money" at its heart, drawing on the hardship of his immigrant family as he sympathised with unemployed workers in a part of Italy that has suffered greatly from the recession.

Addressing about 20,000 people in the Sardinian capital of Cagliari, the Argentinian pontiff said that his parents had "lost everything" after they emigrated from Italy and that he understood the suffering that came from joblessness.

"Where there is no work, there is no dignity," he said, in ad-libbed remarks after listening to three locals, including an unemployed worker who spoke of how joblessness "weakens the spirit". But the problem went far beyond the Italian island, said Francis, who has called for wholesale reform of the financial system.

"This is not just a problem of Sardinia; it is not just a problem of Italy or of some countries in Europe," he said. "It is the consequence of a global choice, an economic system which leads to this tragedy; an economic system which has at its centre an idol called money."

The 76-year-old said that God had wanted men and women to be at the heart of the world. "But now, in this ethics-less system, there is an idol at the centre and the world has become the idolater of this 'money-god'," he added.

Sardinia, one of Italy's autonomous regions with a population of 1.6 million, has suffered particularly badly during the economic crisis, with an unemployment rate of 20%, eight points higher than the national average, and youth unemployment of 51%.

Last summer the island's hardship became national news when Stefano Meletti, a 49-year-old miner, slashed his wrists on television during a protest aimed at keeping the Carbosulcis coal mine open.

Urging people not to give up hope even in the harsh economic climate, Francis also called on them to fight back against the "throwaway culture" he said was a by-product of a global economic system that cared only about profit. It was, he said, a culture that saw the most vulnerable society become marginalised.

"Grandparents are thrown away and young people are thrown away," he said. "And we must say no to this throwaway culture. We must say: 'We want a fair system; a system that allows everyone to move forward.' We must say: 'We do not want this globalised economic system that does so much harm.' At the centre has to be man and woman, as God wants – not money."

His own father, he recalled, had suffered great hardship after moving from northern Italy to Argentina in the 1920s. He went "a young man … full of illusions" of making it in the new world, but soon found there was no work to be had. "I didn't see it; I had not yet been born. But I heard of this hardship at home … I know it well," said Francis.