United States President Barack Obama has expressed surprise at being awarded the Nobel Peace Prize, saying he felt "deeply humbled" and regarded it as a "call to action".
President Barack Obama was awarded the honour for his calls to reduce the world's stockpile of nuclear weapons and working for world peace.
"I do not view it as a recognition of my own accomplishments but rather an affirmation of American leadership," he said at the White House.
"I will accept this award as a call to action, a call for all nations to confront the common challenges of the 21st century."
The Nobel Committee said: "very rarely has a person captured the world's attention to the same extent as Mr Obama and given its people hope for a better future."
It praised the president for "his extraordinary efforts to strengthen international diplomacy and cooperation between peoples," citing his fledgling push for nuclear disarmament and his outreach to the Muslim world.
The first African American to hold the country's highest office, Mr Obama has called for disarmament and worked to restart the stalled Middle East peace process since taking office in January this year.
In September, Mr Obama chaired a historic meeting of the United Nations Security Council, which unanimously approved a US-drafted resolution calling on nuclear weapons states to scrap their arsenals.
Mr Obama is the third senior US Democrat to win the prize this decade after former vice-president Al Gore won in 2007 and former president Jimmy Carter in 2002.
Mr Obama will go to Oslo to personally accept the prize on 10 December and will donate the $US1.4 million prize money to charity.
'Great things expected'
Nobel Committee Chairman Thorbjoern Jagland rejected suggestions from journalists that Obama was getting the prize too early. "We hope this can contribute a little bit to enhance what he is trying to do," he told a news conference.
German Chancellor Angela Merkel said it was an incentive to Mr Obama to do more for peace, while in South Africa, Archbishop Desmond Tutu said the award showed great things are expected of the US president.
Afghan president Hamid Karzai expressed appreciation of Mr Obama's creation of friendly international relations, the BBC reports.
Afghanistan's Taliban spokesman Zabihullah Mujahid, told the Reuters news agency it was absurd to give a peace award to a man who had sent 21,000 extra troops to Afghanistan.
An aide to Iranian president Mahmoud Ahmadinejad said the award should prompt Mr Obama to work towards ending injustice.
The award won praise from Nobel laureates Nelson Mandela, Mikhail Gorbachev and Jimmy Carter.