A two-day conference on aid to Afghanistan closed Tuesday with pledges of more than $4.5 billion, but officials warned the challenge now is seeing the money gets to where it needs to go.

Organizers said that more than $1.8 billion was earmarked for the current year. The remaining $2.7 billion would be distributed by the donors over the next several years.

The United States, Japan and the European Union opened the meeting Monday by offering about $1.3 billion in pledges. But other contributions were smaller, such as $5 million promised by Turkey. Some countries gave no figures at all. At least 25 countries indicated they would contribute.

Few details were given about the rules for spending the aid money. Often, donor countries require their aid be used to buy goods from companies in those countries. Private aid groups have expressed concerns about such conditions.

"I regard it as a very, very good start," World Bank President James Wolfensohn said Tuesday. "I think the important thing is to get things moving forward in an atmosphere of uncertainty."

According to the final statement, the money was offered on the condition that all Afghan ethnic groups would make an active contribution to the goals of reconstruction and reconciliation.

An initial needs assessment prepared by the World Bank and two other international organization estimated that $1.7 billion would be needed to pay for the first year of reconstruction.

"We all know that it's going to be tough to make sure that the money gets to the place that it should go," Wolfensohn said. "But I think with a proper transparent system, with a lot of auditing, with accounting, there's a fair chance that we'll get most of the money where it's supposed to go."

Briefing reporters Tuesday, a senior U.S. delegation official agreed that pledges in Tokyo for the first year "exceeded expectations."

He added, however, that managers of the global aid drive would have to lean on some countries to give more.

Donations fell short of the $10 billion, five-year goal that was floated by U.N. Secretary-General Kofi Annan during his opening address Monday.

But that was mainly because none of the big donors — the United States, Japan, the European Union and Saudi Arabia — made a pledge spanning more than three years. Congressional budgetary procedures prevent the United States from extending its $296 million pledge past this fiscal year, which ends in September.

Delegates consider this a make-or-break chance for Afghan Prime Minister Hamid Karzai, who is trying to collect funds while the world's attention is still focused on Afghanistan.

On Monday, Karzai assured the delegates that his post-Taliban government was committed to free-market policies, advancing human rights and wiping out terrorism.

Secretary of State Colin Powell promised $296 million in the current fiscal year, telling Karzai that "the American people are with you for the long term."

Afghanistan is beginning reconstruction nearly from scratch. Decades of war have all but leveled the country's infrastructure; the central bank was looted in the last days of the ousted Taliban regime; and government employees have not been paid for months.

Karzai's plea came as he embarked on his first world tour to stump for support and solidify his power base in Kabul. Bringing home a bundle in aid will help him do that.

"I stand before you today as a citizen of a country that has had nothing but disaster, war, brutality and deprivation for many years," Karzai said. About two-thirds of Afghan adults are illiterate, and nearly 3,000 people are maimed by land mines every year.

The top U.N. priorities are establishing an Afghan police force, filling the coffers of the interim government and getting farmers back in the fields to plant crops.

Japanese Prime Minister Junichiro Koizumi said his country, the world's second-richest, will contribute up to $500 million over the next three years, with $250 million disbursed in the first year.

The European Union will contribute about $487 million this year, of which $310 million will come from member states and $177 million from the European Commission. Britain promised an additional $295 million over five years.

Conference co-host Saudi Arabia added another $220 million over the next three years. The World Bank and Asian Development Bank pledged $500 million each over the next 2 years in low-interest and no-interest loans.