WASHINGTON/TOKYO - The United States deflected mounting criticism of its treatment of captured Taliban and al Qaeda fighters on Tuesday as Afghanistan walked away from an international conference with $4.5 billion in newly pledged aid to rebuild the war-ravaged country.

Amid international calls to treat the detainees being held at a U.S. military base in Cuba as prisoners of war, U.S. Defense Secretary Donald Rumsfeld insisted they were being treated humanely. Al Qaeda and Osama bin Laden are blamed by Washington for the Sept. 11 attacks on the United States that killed more than 3,000 people.

"Whatever the detainees' legal status may ultimately be determined to be, the important fact from the standpoint of the Department of Defense is that the detainees are being treated humanely," Rumsfeld said.

Bolstered by the promise of billions of dollars in international aid, Afghan officials pledged to battle corruption amid concerns over how the money would be distributed and calls to eradicate opium production in Afghanistan, the world's leading opium producer.

At the two-day aid conference in Tokyo, donor countries, many of which provided support for the military campaign in Afghanistan, pledged more than $4.5 billion to rebuild the country, of which $1.8 billion will be provided this year.

"We will be a Samurai against corruption," interim leader Hamid Karzai, dressed in his trademark green and purple striped robe, reassured donors in Tokyo.

Swift, substantial aid was seen as critical to the survival of the month-old but penniless interim administration.

Karzai had told delegates from more than 60 countries and organizations he hoped to return "with my hands full" to a country where life expectancy is just 44 years and one in four children dies before the age of 5.

"We are happy with the result of the conference we had today and yesterday and I hope we can go back to our people and give them the good news," Karzai told a news conference.

"And I also hope that the pledges made by the international community are made true immediately," said Karzai, 44, who later emerged unscathed from a car accident on a Tokyo expressway.

As he spoke, Afghan civil servants were receiving their first salary payment in six months -- $50 each.

On the streets of Kabul, residents cynical about government promises after two decades of successive communist, Muslim rebel and fundamentalist Taliban rule said the funds should be distributed under United Nations control to ensure the money is used to rebuild the country, not enrich its leaders.

"We hope government officials won't just use this money for themselves," traffic policeman Mohammad Sharif said.

Amid mounting international concern about treatment of the detainees, a U.S. judge in California said he had "grave doubts" whether he had the authority to consider a lawsuit filed by civil rights advocates challenging the detentions.

Americans by and large were unmoved by international protests over the detainees plight, according to interviews and unscientific surveys taken by news organizations.

"They've threatened to kill other Americans ... they're willing to die for a cause and kill innocent people, so they get what they deserve," said Stuart Lorber, a 44-year-old from New York City. "They're getting housing, they're getting food, they're getting medical attention."

The U.S. military has airlifted 158 detainees captured in Afghanistan to a makeshift prison at the U.S. Navy base at Guantanamo Bay, which is on permanent lease from Cuba. Another 275 prisoners are being held in Afghanistan.

Germany and Switzerland said the detainees should be treated as prisoners of war, echoing concerns by the International Committee of the Red Cross and by U.N. Human Rights Commissioner Mary Robinson.

Amnesty International in London said it was alarmed at the veil of secrecy surrounding prisoners at the camp, saying that it feared the detainees were being subjected to techniques traditionally used to "break" prisoners before interrogation.

International outrage over treatment of the Cuba detainees, some of whom have threatened to kill American soldiers if given the chance, was fanned by pictures of the prisoners handcuffed and shackled, wearing ear muffs and blacked-out goggles.

But Rumsfeld said allegations the captured al Qaeda and Taliban fighters were being mistreated were "just plain false," and rejected claims they should be afforded status as prisoners of war under international law.

At a Pentagon briefing, Rumsfeld said the detainees were restrained while they were being transported from Afghanistan. They wore surgical masks and ear pieces to protect them against the spread of tuberculosis and noise from the combat transport planes.

The controversial photographs of kneeling detainees dressed in red jumpsuits were taken as they were kneeling on the ground in a fenced-in corridor waiting to have the headpieces removed before they were escorted to their cells.

"I think that a lot of people saw that and said, 'My goodness, they're being forced to kneel,' which is not true," Rumsfeld said.

Meanwhile, American-born Taliban fighter John Walker Lindh was to be handed over to U.S. prosecutors and returned to the United States this week, he said. The 20-year-old Muslim convert from California was charged with conspiring to kill U.S. nationals and providing support to al Qaeda.

The aid package cobbled together in Tokyo came with strings attached, as international donors insisted the impoverished country, the world's top opium producer, take steps to eradicate its most lucrative cash crop.

Although Karzai's administration has renewed a Taliban-era ban on opium poppy production, the raw material for some two-thirds of the world's illicit heroin supply, the drug trade has remained a critical source of income for Afghan farmers.

International aid workers have been struggling to help farmers switch to other crops, like cotton, but said it would take years to rebuild a sector that employs about eight in 10 people in Afghanistan.

"Everything has been wrecked, destroyed -- we're nowhere near where we were a quarter of a century ago," said Mohammed Murad, head of the U.N. Food and Agriculture Organization office in southwest Afghanistan.

Meanwhile, tribal rivalries threatened to undermine Kabul's fragile interim government as southern Afghan tribal leaders vowed to clear neighboring Helmand province of what they said were hostile fighters backed by Iran.

Provincial government spokesman Abdul Ali said action was planned against western Herat warlord Ismail Khan, but played down statements by the head of Kandahar's intelligence service, Haji Gullalai, who said 20,000 troops were poised to attack. Nampa-Reuters