Pounding rain drenched the wrecked city of Banda Aceh (search) and aftershocks shook the area Saturday, adding to the misery of homeless earthquake and tsunami survivors and heightening fears of waterborne diseases. Flash floods in Sri Lanka forced evacuations and thwarted aid deliveries.

Worldwide donations to aid those battered by the huge waves that slammed Asian and African nations approached $1 billion, and a steady stream of foreign military aircraft touched down in the epicenter of the disaster, the Aceh province on the northern tip of Indonesia's Sumatra island.

Nine U.S. helicopters dropped off supplies at decimated coastal cities — trying to circumvent the bottlenecks that have seen thousands of boxes of food, medicines, water, tents and blankets stacking up at warehouses with not enough hands to get them to survivors. Officials said they were trying to ramp up distribution as fast as possible.

"The scale of the disaster is just too big," said Andi Mallarengen, spokesman for Indonesian President Susilo Bambang Yudhoyono (search). "We can bring in the aid, food, but we need manpower to distribute them."

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Six days after the earthquake and tsunamis, the confirmed death toll passed 123,000. U.N. humanitarian chief Jan Egeland (search) estimated the number of dead was approaching 150,000.

Japan increased its pledge of aid from $30 million to $500 million, the largest single nation donation yet. A day earlier, the United States raised its promise of help tenfold to $350 million.

"Our contributions will continue to be revised as the full effects of this terrible tragedy become clearer," President Bush said Friday. Britain has pledged $95 million, Sweden $75 million and Spain $68 million.

Flash floods in eastern Sri Lanka on Saturday forced the evacuation of 2,000 people from low-lying areas already affected by the tsunami, officials said.

Police officer Neville Wijesinghe said several roads leading to the eastern town of Ampara, one of the worst hit by the tsunami, were blocked by flood waters, preventing aid trucks from getting through for several hours.

Aftershocks rattled the region, including a 6.5-magnitude quake 215 miles west of Banda Aceh on Saturday, the U.S. Geological Survey said. Smaller aftershocks hit northern Sumatra and the Nicobar and Andaman islands, a remote Indian archipelago just north of Sumatra. The National Oceanic and Atmospheric Administration said the aftershocks were too small to trigger tsunamis.

Hundreds of refugees in Nicobar and Andaman massed in eight camps near the territory's capital, Port Blair, swarming around officials to plead for supplies. Many had walked long distances through dense jungles from their devastated villages to reach airfields from which they were brought to the capital.

"There is starvation. People haven't had food or water for at least five days. There are carcasses. There will be an epidemic," Manoranjan Bhakta, Andaman's lawmaker to the federal parliament, told The Associated Press after being surrounded on a roadside by people demanding food and water for stranded family members.

A U.S. battle group led by the aircraft carrier USS Abraham Lincoln arrived off the shores of Sumatra, and Seahawk helicopters began ferrying supplies from the ships to the ravaged shore.

A flotilla carrying Marines and water purifying equipment was bearing down on Sri Lanka, meanwhile, and a former staging base for B-52 bombers in Thailand roared with the take-offs and landings of giant cargo planes.

In the provincial capital of Banda Aceh, tons of rice, water, tarps and medical supplies began arriving in trucks and huge, C-130 aircrafts.

Saturday's rainstorm in Banda Aceh was the first since last Sunday's disaster. Health workers have warned that heavy rain could spread diseases like cholera and diarrhea. Thousands of uncollected corpses remain in and around the city.

At one refugee camp on the grounds of the airport, hundreds of people spent a damp night under plastic sheets. Mothers nursed babies while others tried to light a fire with damp matches.

"With no help we will die," said Indra Syaputra. "We came here because we heard that we could get food, but it was nonsense. All I got was some packets of noodles."

In the northern Aceh town of Bireun, officials warned that as many as 18,000 refugees were threatened with disease and starvation unless aid arrived soon.

"The government has been too slow in handling distribution of aid," said Riswan Ali, a refugee acting as a coordinator in Bireun. "We need water. Our children are sick. They need food and medicine, please help us."

Indonesia reported 80,000 deaths; Sri Lanka 28,700, India just short of 9,000. Thailand's toll stood at 4,800, just over half of them foreign tourists, but 6,500 people were missing and presumed dead.

Thailand's prime minister, Thaksin Shinawatra said Saturday that his country would investigate why no warnings were issued ahead of the tsunamis.

In the hardest-hit country, Indonesia, the official death toll stood at more than 80,000, but officials said it could reach 100,000.

"We mourn, we cry and our hearts weep to witness thousands of victims sprawled everywhere," said Yudhoyono, the president. "We witness those survivors still living in desperation and sinking into sadness and confusion."