Italy's economy grew 0.4% in the first quarter thanks to firm domestic demand, national statistics bureau ISTAT said today.
The reading was a sharp increase from an earlier preliminary estimate and improved the prospects for the full year.
Preliminary data issued last month pointed to growth of just 0.2% between January and March.
On a year-on-year basis, first quarter growth was revised up even more sharply to 1.2% from a previous estimate of 0.8%.
ISTAT also revised up growth for the fourth quarter of last year to show a 0.3% rise quarter-on-quarter.
This was up 1.1% year-on-year from a previously-reported 0.2% on the quarter and 1% year-on-year.
The revisions significantly improve the prospects for the government of Prime Minister Paolo Gentiloni to meet or exceed its full year 2017 growth target of 1.1%.
In the first quarter, Italy's growth was driven by firm consumer spending and a large increase in inventories which offset a negative contribution from trade flows.
Italy's economy has been the most sluggish in the euro zone for more than a decade, and the government's 1.1%t growth forecast for this year would again be only around half the average expected for the region as a whole.
However, the steep upward revision of GDP data is a first sign of so-called "hard" data, such as industrial output and GDP, beginning to reflect buoyant surveys of sentiment and activity levels among purchasing managers in the manufacturing and services sectors.
In the first quarter the euro zone as a whole grew by 0.5% from the previous three months and by 1.7% year-on-year, according to Eurostat data.
ISTAT said so called "acquired" growth at the end of the first quarter stood at 0.9%.
That means that if there were to be no growth in the final three quarters of the year, full-year GDP would still rise 0.9%.