The Norwegian Nobel Committee contrasted Carter's success in finding peace between Egypt and Israel through diplomacy with President Bush's vow to oust Saddam Hussein, by force if necessary.
``It (the award) should be interpreted as a criticism of the line that the current administration has taken,'' said Gunnar Berge, the Nobel committee chairman. ``It's a kick in the leg to all that follow the same line as the United States.''
Although the committee has often used the prize to send a political message, it rarely makes such a direct comment. Other members of the committee distanced themselves from Berge's statement, calling it his personal view.
``In the committee, we didn't discuss what sort of interpretation of the grounds there should be. It wasn't a topic,'' committee member Hanna Kvanmo was quoted as telling the Norwegian news agency NTB.
The committee cited Carter's ``vital contribution'' to the Camp David Accords between Israel and Egypt and his efforts in conflict resolution on several continents and the promotion of human rights after his presidency.
``In a situation currently marked by threats of the use of power, Carter has stood by the principles that conflicts must as far as possible be resolved through mediation and international co-operation based on international law, respect for human rights, and economic development,'' the citation said, without mentioning Iraq.
The award is worth $1 million.
Bush called his predecessor to congratulate him and the two spoke for a few minutes.
``It was a friendly conversation,'' White House press secretary Ari Fleischer said, adding that Bush was ``pleased to be able to congratulate a former American president on winning such a prestigious award.''
Fleischer declined to respond to Berge's statement.
``The president thinks this is a great day for Jimmy Carter and that's what he's going to focus on,'' he said.
In a statement posted on the Carter Center's Web site, the 39th president said, ``My concept of human rights has grown to include not only the rights to live in peace, but also to adequate health care, shelter, food, and to economic opportunity. I hope this award reflects a universal acceptance and even embrace of this broad-based concept of human rights.''
In an interview later on CNN, Carter declined to comment on the implied criticism of the Bush Administration's handling of the crisis with Iraq, but said he would have voted no yesterday on the congressional resolution allowing the president to use force against Iraq.
But Carter said he felt that the Bush Administration had come a long way from earlier threats to attack Iraq, unilaterally if necessary.
``I listened with care the other night to President Bush's speech, and he said ... just the opposite. That we would indeed work through the United Nations and that we did not have any intention of working unilaterally.''
Carter has said his most significant work has been through the Carter Center, an ambitious, Atlanta-based think tank and activist policy center he and wife, Rosalynn, founded in 1982 and which celebrates its 20th anniversary this year.
``It's very gratifying to me to see our folks at the Carter center so recognized,'' Carter said.
Perhaps his crowning achievement as president was the peace treaty he negotiated between Egyptian President Anwar Sadat and Israeli Premier Menachem Begin. Carter kept them at Camp David for 13 days in 1978 to reach the accord; Sadat and Begin shared the Nobel Peace Prize.
The Nobel committee said Carter, who was in the White House from 1977-1981, didn't share in that prize because he wasn't nominated in time.
Carter is the third American president to be awarded the prize. Woodrow Wilson received it in 1919 for his role in establishing the League of Nations, a forerunner to the United Nations. Theodore Roosevelt received the prize in 1906 for his role in establishing several peace treaties.
The last American to receive the peace prize was Jody Williams and her International Campaign to Ban Landmines in 1997.
Former Secretary of State Henry Kissinger shared the 1973 award with Le Duc Tho of then-North Vietnam, who declined it.
The five-member committee made its decision last week after months of secret deliberations as it sought the right message for a world still dazed by the Sept. 11 terror attacks, the war on terrorism that followed and concern about a possible U.S. military strike against Iraq.
Afghan President Hamid Karzai, one of this year's nominees, had called a press conference in Kabul in advance of the announcement, but ended up congratulating Carter.
``He deserved it better than I, and he won it, and I'll try for next year,'' he said at his presidential palace in Kabul.
Portuguese President Jorge Sampaio said the prize was ``a just reward'' and ``wholly deserved.'' He singled out Carter's efforts to find a peaceful solution for East Timor, a former Portuguese colony annexed by Indonesia.
Carter, a Democrat and former Georgia governor, rose from a small-town peanut farmer to the nation's presidency in 1976 after a campaign that stressed honesty in the wake of the Watergate controversy.
But he returned home after a landslide loss to Republican Ronald Reagan in 1980, his candidacy undermined by double-digit inflation, an energy crunch that forced Americans to wait in line for gasoline, and the 444-day hostage crisis in Iran.
Carter overcame the voter repudiation and has doggedly pursued a role on the world stage as a peacemaker and champion of democracy and human rights.
He helped defuse growing nuclear tensions in Korea, then helped narrowly avert a U.S. invasion of Haiti in 1994, as well as leading conflict mediation and elections monitoring efforts around the world.
Last year's award was shared by the United Nations and its secretary-general, Kofi Annan.
The peace prize announcement capped a week of Nobel prizes after the awards for literature, medicine, physics, chemistry and economics were announced in Sweden's capital, Stockholm.
The Norwegian Nobel committee received a record 156 nominations — 117 individuals and 39 groups — by the Feb. 1 deadline.
The list remains secret for 50 years, but those who nominate sometimes announce their choice with known nominees this year including Karzai, Bush and British Prime Minister Tony Blair.
The first Nobel Peace Prize, in 1901, honored Jean Henry Dunant, the Swiss founder of the Red Cross.
The prizes were created by Swedish industrialist Alfred Nobel in his will and always are presented on Dec. 10, the anniversary of his 1896 death.