European Union leaders in Norway to collect the Nobel peace prize Sunday countered criticism of this year's award, saying Europe will emerge more united from the economic crisis and remain on a course of peace.

"Europe is going through a difficult period," EU president Herman Van Rompuy told a packed news conference on the eve of the awards ceremony.

"We are working hard ... We will come out of this time of uncertainty and recession stronger than we were before."

Van Rompuy, along with European Commission president Jose-Manuel Barroso and European parliament chief Martin Schulz will collect the Nobel medal, diploma and almost million-euro award on behalf of the bloc in Oslo on Monday.

But as the EU's worst crisis in six decades lays bare splits between have and have-not states, the Nobel Committee has come under attack for its move to commend the EU for turning a continent at war into a continent at peace.

Critics fear a return of extremist groups such as in Greece, and point to the threat of serious social unrest as unemployment hits record levels, leaving one out of two youths jobless in Greece and Spain.

In Oslo, capital of eurosceptic Norway, hundreds turned out for a candlelight protest in the snowy streets, chanting "No peace prize for our time."

"This prize shouldn't be seen as part of the Norwegian debate on whether we should or not join the EU," said Nobel Committee chairman Thorbjoern Jagland.

Barroso, who heads the EU executive that handles day-to-day business, too said the EU would emerge more united from the sovereign debt crisis.

"We were not fully equipped to cope with a crisis of this magnitude," Barroso conceded. But the answer for the future was "more integration, not less."

The crisis is undermining solidarity and generosity inside the EU.

Efforts last month to agree a new multi-year budget collapsed month in an ugly showdown between the rich nations of northern Europe and the struggling economies of the south. The bloc too split over support to the Palestinian bid for a status upgrade at the UN.

And though it is preparing to further expand by embracing Croatia as its 28th member next year, the 27-nation union will stand divided at Monday's ceremony to collect the prize.

Half a dozen EU leaders, including Britain's premier David Cameron, are snubbing an event.

On hand will be leaders of the "big two" powers France and Germany, Francois Hollande and Angela Merkel. But relations between these two are rocky, notably holding up a deal to set up a banking union that comes down to the wire four days after the Nobel ceremony.

The deal on the banks is key to the future of the EU, which stands at a crossroads between more union and more federalism -- or more uncertainty.

Nobel Committee chairman, the ardently pro-European Thorbjoern Jagland, however justified the choice by the absence of conflict on a scale seen in the two world wars of the 20th century.

"The disputes and dramas have never led to war. On the contrary they have led to compromises,"

Shulz, a German Socialist at the head of the European parliament, said the award must be "a warning, an alert" to stick to the ideals of the founders of the bloc in the aftermath of World War II.