The European Union's president Thursday invited all 27 EU leaders to travel to Oslo to collect the Nobel Peace Prize and said the bloc's current hardships were nothing compared to those faced by the founding fathers.

"To mark this joyful occasion, I hope all EU heads of state or government will be able to join celebrations in Oslo in December," Herman Van Rompuy said at the start of an EU summit.

Van Rompuy posted the message on Twitter moments after German Chancellor Angela Merkel and French President Francois Hollande entered the secure summit hall in Brussels, with a brief live video feed showing Merkel shaking her head as Hollande leant over to speak as they walked in side by side.

The Nobel Committee announced on Friday that it had awarded its flagship prize to the EU for bringing more than half a century of peace to a continent ripped apart by World War II, in a decision met with praise and ridicule in equal measure.

The awarding of the prize is "a tremendous honour for all of our countries, for all our institutions and above all, for all our citizens," said Van Rompuy.

"We are facing serious difficulties today but we can draw confidence by remembering that the obstacles the builders of Europe had to overcome were frankly more daunting," the Belgian said.

"They had to rebuild the continent wrecked by violence, by dictatorships and they succeeded."

European Parliament President Martin Schulz said on Wednesday that he, European Commission President Jose Manuel Barroso and Van Rompuy would jointly pick up the award, worth about one million euros ($1.2 million), on December 10 in Oslo.

He said however that a meeting with Barroso and Van Rompuy had failed to reach agreement on who would deliver the acceptance speech.

The Commission has said negotiations were underway with the Nobel Committee to resolve protocol and other issues.

The EU -- many of its states riven with debts collectively worth trillions of euros -- also has to decide what to do with the prize money.

"May this Nobel Prize be seen as a recognition of a great joint endeavour and a strong appeal to preserve Europe as a continent of peace, progress and prosperity for the next generation," said the president.