Plans to put up the price of rail tickets drew criticism on Tuesday from consumer groups and trade unions.
The loss-making national railways FS announced on Monday that fares for its high-speed and Eurostar services would increase a further 10% in October.
The price of such tickets was already hiked by 10% last month.
Commuters, meanwhile, will be hit by a 3.5% rise in local train fares.
FS, which is in heavy debt, said the rises were needed to guarantee services and stressed that ticket prices had remained frozen since 2000.
Consumer associations Adusbef and Federconsumatori urged the government to block the increases, which they described as "scandalous and intolerable".
They threatened to take FS to court, arguing that services had to improve before the company could consider putting up prices.
Another group, Adiconsum, said the increases were "absurd" and "unthinkable unless the company improves the efficiency, punctuality and cleanliness of the trains".
UIL, one of Italy's biggest unions, said that "passengers shouldn't be the ones to pay for FS's consolidation".
But Junior Economy Minister Vincenzo Visco defended FS.
"Without these increases, the company will collapse," he said.
"FS's economic situation is one of the worst legacies of the previous government, which blocked fares for five years when an increase of 2% per year would have been more rational and easier to digest... A hefty increase has become inevitable," Visco said.
But consumer groups and unions accuse FS of mismanagement and overpaying its bosses.
They note that former state-appointed FS chief Elio Catania, who resigned last September, received a severance package of five million euros from the railway company.
During his two-year stint at the company, Catania was on just under two million euros a year. Although he was called in to turn the company around, when he left it was in the red to the tune of 1.6 billion euros.
FS, meanwhile, whose debts have now risen to almost 2 billion euros, defended the fare increases as a vital part of its industrial plan for the period 2007-2011.
It said they would net the company an additional 90 million euros.
"The price rises will cover only a part of the financial burden that the company has accumulated over the years," it said in a Monday statement.
While admitting that it planned to put up rail fares by 5% per year from 2009-2011, FS stressed that the increases for less profitable and local services would not exceed 3% including this year.
