Italy's tax police uncovered 15.3 billion euros in undeclared income in 2006 as part of state efforts to reduce the scale of the country's underground economy.
Business activity which is invisible to tax authorities remains "significant and shows no signs of diminishing," tax police officials said during the presentation of 2006 results on Wednesday.
Police also found 6,950 total tax evaders and VAT dodging on 3.5 billion euros of revenue.
Economy Minister Tommaso Padoa Schioppa last week repeated the government's pledge to get tough with tax dodgers and curb the black economy, which independent estimates say equals almost 30% of GDP.
"Tax evasion is a pathology of epidemic proportions. We will reduce it to a sporadic pathology," he said.
The government's hefty 2007 budget contains a number of anti-tax evasion measures. They are close to Premier Romano Prodi's heart because he has promised to finance cuts in payroll taxes with the money recovered.
A recent report by the independent Eurispes institute said underground businesses generated more than 300 billion euros a year in Italy.
Some 5.65 million Italians regularly work off the books while tax evasion deprives the state of more than 132 billion euros a year, Eurispes said.
In a 2003 report, the International Monetary Fund issued data that corresponded with Eurispes' findings.
