Former Polish president and Solidarity leader Lech Walesa, a 1983 Peace Prize laureate, is shown at a concert in Gdansk on June 4, marking the 20th anniversary of historic elections in Poland. (Alik Keplicz/Associated Press)

The selection of U.S. President Barack Obama as the 2009 Nobel Peace laureate has raised questions worldwide about whether it is too early in his mandate to bestow the award.

The prize citation said Obama, 48, has shown "extraordinary efforts to strengthen international diplomacy and co-operation between people."

The committee attached special importance to Obama's vision and work for a world without nuclear weapons, his focus on multilateral diplomacy and his efforts to ease tensions with the Muslim world.

But Obama has only been in the White House for about nine months and, given the prize's Feb. 1 nomination deadline, would have been put forward while in office for less than two weeks.

Nobel observers said Friday that selecting Obama so early in his presidency is unexpected.

"So soon? Too early," said former Polish president Lech Walesa, a 1983 Nobel Peace Prize laureate. "He has no contribution so far. He is still at an early stage. He is only beginning to act."

Many of Obama's policies are still in their early stages and there has been a lack of tangible progress on several of his administration's vital goals so far, including peace in the Middle East, persuading Iran to curb its nuclear program and improving relations with North Korea.

"This is probably an encouragement for him to act," Walesa said. "Let's see if he perseveres. Let's give him time to act."

Even Obama told reporters in the White House Rose Garden on Friday that he was not sure he had done enough to receive the prestigious award. But the president said he would accept the honour as a "call to action" to work toward greater international harmony and more environmentally sustainable practices.

In the United States, Republican politicians criticized the win as an example of Obama's "star power" rather than meaningful accomplishments.

'Message of hope'

The award shows great things are expected from Obama, said South African Archbishop Desmond Tutu, who won the Peace Prize in 1984.

"It is an award that speaks to the promise of President Obama's message of hope," Tutu said.

In Kenya, where Obama's father was from, citizens praised the award as a win for Africa.

"We need an Obama here in Africa," Kenyan engineer Humphrey Oguto said. "He's done a lot in just a little time.… Our leaders have done nothing for years."

Mohamed ElBaradei, director general of the International Atomic Energy Agency in Vienna, who is also a former Peace Prize winner, said Obama has already provided outstanding leadership in the effort to prevent nuclear proliferation.

"In less than a year in office, he has transformed the way we look at ourselves and the world we live in and rekindled hope for a world at peace with itself," ElBaradei said Friday. "He has shown an unshakeable commitment to diplomacy, mutual respect and dialogue as the best means of resolving conflicts."

Iranian President Mahmoud Ahmadinejad said his country is "not upset" by the announcement of the prize, but only if Obama removed the U.S. veto power in the UN Security Council would it prove the award was given to him legitimately.

"We hope that by receiving this prize he will start taking practical steps to remove injustice in the world," a spokesman for Ahmadinejad said.

'Long way to go'

Giving the award to an American president who has sent more troops to Afghanistan and further escalated the war is unjust, Taliban spokesman Zabihullah Mujahid told Reuters.

The Palestinian Islamist movement Hamas also called the citation premature.

"Obama has a long way to go still and lots of work to do before he can deserve a reward," Hamas official Sami Abu Zuhri told Reuters. "Obama only made promises and did not contribute any substance to world peace."

American Peace Prize laureate Jody Williams, who won in 1997, said she sees the award as a way to put "additional pressure on Obama to live up to the promise of his vision."

The president has to prove that his administration's goals are not just rhetoric, Williams said. "The words are terrific but we want to see the actions back them up," she said. "I want to see him make it into a reality."

Analysts said the world is also still waiting to see progress from Obama on climate change, human rights, the war in Afghanistan and the United States' presence in Iraq.

Norwegian Nobel committee chair Thorbjorn Jagland told CBC News the committee expected criticism about the choice of Obama. But the prize is meant to help "strengthen his role and his policy," he said.

Although Obama has been president for less than a year, it has been "enough time to inspire the world," Jagland said.

Some Nobel analysts have said the win is meant more as a rejection of the policies of Obama's predecessor, George W. Bush. Rather than recognizing concrete achievement, the 2009 prize appeared intended to support Obama's initiatives, analysts said.

"You have to remember that the world has been in a pretty dangerous phase," Jagland said. "And anybody who can contribute to getting the world out of this situation deserves a Nobel Peace Prize."

French President Nicolas Sarkozy said the prize marks the "return of America into the hearts of the people of the world."

With files from The Associated Press