Pope Francis has condemned arms manufacturers as "hypocrites" if they call themselves Christians.

In hard-hitting unscripted comments to thousands of young people in Turin, the Pope said of arms manufacturers: "They say they are Christians!" He extended his condemnation to people who invested in arms companies, imagining their excuses: "'No no, Father, I do not make [them], I only have my investments in the fabrication of arms.'"

"Why?" he asked. "Because the interests are a bit higher. And so the double-face is money flowing today; to say one thing and do the other. Hypocrisy."

His comments reflected his long-standing hostility to the trade. Last year he told a crowd gathered in St Peter's Square that people producing weapons of war are "merchants of death".

"One day everything comes to an end and they will be held accountable to God," he said.

In his Turin address to young people he also warned against putting too much trust in politicians, saying: "In Europe there is war, in Africa there is war, in Asia there is war. But can I have trust in a world like this? Can I trust the world's managers?

"When I go to give my vote for a candidate, can I trust that they will not bring my country to war? If you put trust only in people, you lose."

He spoke of the Armenian genocide in the early 20th century – though he did not use the word – and of the failure of the Allied forces to stop the Nazi genocide programme. "The great powers had photographs of the railways that brought trains to concentration camps, to Auschwitz, to kill Jews, Christians, Gypsies, homosexuals.

"But tell me, why didn't they bomb them?" he asked. "The great powers, they divided Europe like a cake."

He urged the young people to "go against the current" in resisting consumerism and sexual licence, saying: ""Love is very respectful of people. It does not use people. And, namely, love is chaste. And to you all, young people, in this hedonist world, in this world where there are only commercials, pleasure... I tell you: Be chaste! Be chaste!"

He continued: "It is right to try for a genuine love, that knows to give life, that does not search to use the other for its own pleasure. A love that makes sacred the life of the other person: 'I respect you, I do not want to use you.' It is not easy, we all know the difficulty to overcome this easy and hedonistic conception of love."

Pope Francis also addressed workers gathered in the Piazzetta Reale on the theme of economic justice and the dignity of labour, saying: "A job isn't only necessary for economic reasons but for the human being, for his dignity, his citizenship and for social inclusion. Immigration increases competition, but we don't have to blame the migrants because they are victims of inequality, of this throwaway economy and the wars."

His two-day visit to Turin, the city from which his parents emigrated to Argentina, also saw him pray at the Turin Shroud and meet members of his extended family in the area.