Nobel committee chairman Thorbjoern Jagland said the committee had no position on how to solve the continent’s economic crisis.

‘‘But we send a very strong message that we should keep in mind why we got this Europe after World War II,’’ he said. ‘‘We should do everything we can to safeguard it, not let it disintegrate and let the extremism and nationalism grow again.’’

The road ahead remains difficult.

European leaders enjoyed a period of relative calm over the summer, when it seemed they had built the more centralized institutions that many economists believe are necessary to the stability of the common currency.

But now there are what the economist De Grauwe called ‘‘rear guard battles’’ in which some EU states, notably Germany, appear to be trying to undo or dilute some of those accomplishments, including a proposed banking union and the ability of the European Central Bank to reduce countries’ borrowing costs by buying sovereign bonds.

And perhaps the biggest challenge of all is restoring growth to a region where the economies of many are shrinking. That is unlikely to happen, De Grauwe said, unless EU leaders relax their unrelenting drive for austerity, through which they are creating what he called ‘‘a recession that could have been avoided.’’

Those hit by this recession were not impressed by the prize.

‘‘The peace prize?’’ asked Giorgos Dertilis, who works at an insurance company in Athens. ‘‘The way things are going, what will happen in the immediate future? Peace is the one thing we might not have.’’

George Tzogopoulos, a political analyst from the Hellenic Foundation for European and Foreign Policy, said the prize might help people understand the role the EU has played in preserving peace. But it could also be viewed as ‘‘a hypocritical gesture, because the European Union has so far completely failed to deal with the social dimension of the crisis and problems like poverty and unemployment.’’

Still, German Chancellor Angela Merkel said the Nobel committee had made a ‘‘wonderful decision,’’ and linked it to efforts to salvage the euro, even though the judges didn’t mention the common currency.

‘‘I often say the euro is more than a currency. We shouldn’t forget this in these weeks and months in which we work for the strengthening of the euro,’’ Merkel told reporters at the Chancellery in Berlin. The euro ‘‘has always primarily been about the original idea of Europe as a community of peace and values.’’

Strong reactions to the choice for the $1.2 million award crackled Friday over social media.

‘‘The EU is a unique project that replaced war with peace, hate with solidarity. Overwhelming emotion for awarding of (hash)Nobel prize to EU,’’ Martin Schulz, president of the European Parliament, wrote on Twitter.

‘‘Nobel prize for the EU. At a time Brussels and all of Europe is collapsing in misery. What next? An Oscar for Van Rompuy?’’ said Dutch euro-skeptic lawmaker Geert Wilders, referring to Herman Van Rompuy, president of the European Council.

Normally, the prize committee either honors lifetime achievement or promotes a work in progress.

This year’s award does both, Jagland said, noting it ‘‘looks backward as well as forward’’ by recognizing the EU’s historic role in building peace, even as nationalist forces that once tore the continent apart are again on the rise.

The citation noted the democratic reforms the EU demands of nations who join. It referred to Greece, Spain and Portugal, which joined in the 1980s after emerging from dictatorships, and to the talks with Balkan nations seeking membership following bloody wars in the 1990s.

Europe’s stumbling economy is making it harder for economies around the world to recover and international policymakers are urging more decisive action from the region’s governments to deal with the crippling debt crisis.

The region is the United States’ largest export customer and any fall-off in demand will hurt U.S. businesses — as well as Obama’s election prospects.

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