Scotland's most senior Catholic called on David Cameron on Sunday to introduce a "Robin Hood tax" and to stop protecting his "very rich colleagues" at the expense of the poor.
The head of the Catholic church in Scotland Cardinal Keith O'Brien urged the government to implement the tax on financial transactions to raise money for the poor.
He said: "My message to David Cameron, as the head of our government, is to seriously think again about this Robin Hood tax, the tax to help the poor by taking a little bit from the rich.
"The poor have suffered tremendously from the financial disasters of recent years and nothing, really, has been done by the very rich people to help them."
Cardinal O'Brien said that "immoral" government policies were making the poor pay the price for the failings of the rich.
He also appealed to the Prime Minister: "Don't just protect your very rich colleagues in the financial industry, consider the moral obligation to help the poor of our country."
The cardinal went further by stating that he was not only concerned about people in "abject poverty" but also those who might consider themselves "reasonably well-off.
"People who have saved for their pensions and now realise their pension funds are no more, people who are considering giving up their retirement homes that they have been saving for, poverty affecting young couples ...
"It is these people who have had to suffer because of the financial disasters of recent years and it is immoral."
A Downing Street spokesman said the Budget took two million people on the lowest incomes out of tax altogether.