WASHINGTON - President Barack Obama will accept his Nobel peace prize this week as a war president, and will address the awkward timing of his Afghan troop surge announcement head on, the White House said Monday.

Obama will leave for Oslo on Wednesday and accept the surprise award the next day, on a delicate mission on which he must juggle the status of the prize with his so far limited foreign policy record.

"We'll address directly the notion, I think, that many have wondered, which is the juxtaposition of the timing for the Nobel Peace Prize and his commitment to add more troops into Afghanistan," said Obama's spokesman Robert Gibbs.

"That's obviously something that he will address," Gibbs said. Asked whether Obama would accept the prize as a "war president," Gibbs replied "Exactly."

The choice of Obama as Nobel peace laureate, and his Afghan troop decision, has sparked anger among some critics and spurred activists to plan demonstrations in Oslo which have prompted a massive security operation.

Earlier, in Norway, Benjamin Endre Larsen, the head of umbrella organization Fredsinitiativet organising a demonstration, told AFP "the Peace Prize creates obligations."

"The decision to send additional troops to Afghanistan is sad and cynical and this shows that Obama has not understood his obligations."

"We think that Obama received the prize prematurely, but now that he has it he has to prove himself worthy," he added.

The Norwegian government has earmarked 92 million kroner (S$22.24 million) to cover security needs during Obama's visit - more than 10 times the prize money awarded to the Peace Prize laureate.