PARIS — By naming the European Union the recipient of the 2012 peace prize on Friday, the Norwegian Nobel Committee made an unconventional choice that celebrated the bloc’s postwar integration even as a financial crisis and political infighting threaten to tear it apart.

Members of the Nobel committee lauded six decades of reconciliation among enemies who fought Europe’s bloodiest wars while simultaneously warning against the hazards of the present. The decision sounded at times like a plea to support the endangered institution at a difficult hour.

“We see already now an increase of extremism and nationalistic attitudes,” said Thorbjorn Jagland, the former Norwegian prime minister who is chairman of the panel awarding the prize, in an interview after announcing the award. “There is a real danger that Europe will start disintegrating. Therefore, we should focus again on the fundamental aims of the organization.”

Yet on the very day that the award was announced in Oslo, leading European policy makers again publicly bickered over how to deal with Greece’s bailout. Germany’s finance minister, Wolfgang Schäuble, rejected calls from the French head of the International Monetary Fund, Christine Lagarde, to give Greece more time to make additional spending cuts to rein in deficits.