* FTSEurofirst 300 up 0.8 pct, after 16 pct gain in Q1
* Spanish, Italian shares hit highest since 2010 after PMIs
* Barry Callebaut up 8 pct after posting strong results (Adds detail, quote)
By Alistair Smout and Blaise Robinson
LONDON/PARIS, April 1 (Reuters) - European shares reversed early losses after the first major data of the new quarter showed manufacturing activity across the euro zone accelerated faster than previously thought last month.
Markit's final March manufacturing Purchasing Managers' Index (PMI) was at a 10-month high of 52.2, beating a preliminary reading of 51.9, adding to signs the bloc's economy is recovering.
After Chinese data rattled markets on Wednesday, German manufacturing PMIs beat a preliminary reading and French data showed a less severe contraction than first estimated.
Spanish and Italian PMIs helped both national blue-chip indexes up 1 percent, hitting their highest levels since 2010.
At 1001 GMT, the FTSEurofirst 300 index of top European shares was up 0.8 percent at 1,597.97 points.
The benchmark index surged 16 percent in the first quarter as the European Central Bank pumped out money and the euro weakened.
The oil price fall has eroded earnings growth forecasts for 2015 to a 4.7 percent rise, with downgrades led by oil majors. However, the economic boost of lower energy prices could reverse the downgrade trend.
"The improving economic outlook, for example today's stronger PMI data, coupled with lower input costs (particularly energy costs) and higher overseas earnings thanks to the weaker euro, will drive an earnings upgrade cycle," Neil Wilkinson, European fund manager at Royal London Asset Management, said.
Shares in Swiss chocolate maker Barry Callebaut surged 7.9 percent after it reported higher half-year sales and profits, as cost cuts helped counter the impact of the surging Swiss franc. It also confirmed its mid-term targets subject to currency swings.
Neopost bucked the trend, dropping 6.2 percent after posting disappointing results.
The FTSEurofirst 300's top faller was Fortum, down 7 percent as it traded "ex-dividend" without entitlement to the latest payout and was also cut to "underperform" from "neutral" by Macquarie.
Europe bourses in 2015: link.reuters.com/pap87v
Asset performance in 2015: link.reuters.com/gap87v
Today's European research round-up (Editing by Ruth Pitchford)