* Euro recovers, supported by optimism on Greek aid package
* But lack of detail caps euro's gains
* Solid euro zone data helps; Greek bond spreads narrow (Adds quote, detail)
By Jessica Mortimer
LONDON, April 29 (Reuters) - The euro rose on Thursday, rebounding from a one-year low the previous day on hopes a bail-out plan for debt-stricken Greece would be finalised soon.
Gains were limited, however, as details of the Greece package were thin, leaving uncertainties about the timing and implementation of any deal.
Germany's largest opposition party said it would move quickly to approve German participation, while European Union Economic and Monetary Affairs Commissioner Olli Rehn said the European Union should complete talks "within days". [ID:nBAT005360] [ID:nBRU010773]
However, Rehn said he still could not provide details of the deal, which he said were "conditional on fiscal consolidation".
"Hopes about a package are providing relief for the euro, plus the data was positive too," said BNP Paribas currency strategist Ian Stannard.
"But any rallies are proving to be short-lived because details are still thin on the ground. The market's hopes are built up when a press conference is announced then they are dashed again when there is no new information."
At 1146 GMT, the euro <EUR=> rose 0.4 percent against the dollar to $1.3264.
It was comfortably above a one-year low around $1.3112 hit on Wednesday after Standard & Poor's cut Spain's credit rating by one notch, a day after downgrades to Greece and Portugal.
But the low was hit only briefly, with investors focusing on comments from a German parliamentarian that the aid package for Greece would be worth 100 billion to 120 billion euros over three years. [ID:nBAT005353]
"The market sees a bigger package for Greece, covering three years, as a bigger backstop. This is helping to address some investor fears and giving some support for the euro," said Kenneth Broux, market economist at Lloyds Banking Group.
The euro was also supported by euro zone economic sentiment jumping much more than expected in April, pointing to strengthening economic activity. [ID:nLDE63S0O1]
Spreads between Greek and German bond yields also narrowed on optimism over prospects for a bailout, while an Italian bond auction passed relatively smoothly. [GVD/EUR] [ID:nTAR001527].
A statement from the U.S. Federal Reserve, which offered a more upbeat view of the U.S. economy, helped boost risk sentiment and weighed on the safe-haven U.S. dollar and low-yielding yen.
At the conclusion of its two-day rate setting committee meeting on Wednesday, the Fed maintained its pledge to keep interest rates low for an "extended period" and slightly upgraded some of its economic forecasts. [ID:nN27125552]
"The FOMC did not rock the risk boat in any way whatsoever and much of yesterday's losses across different asset classes were gradually faded," UBS currency strategist Geoffrey Yu said in a note to clients.
The dollar <.DXY> traded down 0.5 percent at 81.932, after rallying to a near one-year high of 82.714 on Wednesday.
The yen was broadly flat versus the dollar <JPY=> at 94.03 yen, while euro/yen <EURJPY=R> rose 0.4 percent to 124.73 yen.
(Additional reporting by Neal Armstrong)