BANTUL, Indonesia (AP) - U.S. Marines joined an international effort to deliver aid and medical care to nearly 650,000 Indonesians displaced by a devastating earthquake, as hopes faded of finding more survivors.

Two U.S. Marine cargo planes carrying a mobile field hospital landed Tuesday in Yogyakarta, closest to the quake area in central Java, after cracks in the airport runway were patched.

A disaster assistance response team from the U.S. Agency for International Development is being readied and the amphibious assault ship USS Essex, which has extensive medical facilities, is en route to the area, White House deputy press secretary Dana Perino said.

The United States also increased its aid contribution to $5 million.

The United Nations said at least 21 other countries have joined the effort to help those left homeless by Saturday's magnitude-6.3 quake, which killed more than 5,800 people. An estimated 647,000 people were displaced by the quake, nearly a third of them homeless and the rest staying with relatives, said Bambang Priyohadi, a senior provincial government official.

The government said Wednesday the temblor destroyed more than 135,000 homes, reducing them to piles of bricks, tiles and wood in less than a minute. Priyohadi based the displaced figure on the number of homes destroyed and a family index of 4.8 people per house.

The main hospital in hardest-hit Bantul district was still overwhelmed, with 400 patients for just over 100 beds, and doctors complained of a lack of supplies.

"We are short of splints, gauze, even beds,'' said Dr. Hidayat, the hospital's earthquake emergency coordinator, adding that 90 percent of the victims had bone fractures. "The minute we get fresh splits, they are gone.''

But conditions improved at several other hospitals, where parking lots and hallways that had been filled with hundreds of victims in the days after the quake were clear, with most patients now being treated in beds.

Workers removed a tent outside Yogyakarta's largest hospital, Sardjito, that had been used to shelter the injured.

The U.N.'s top humanitarian official said the aid effort was going well, and there had been major improvements in coordination among aid organizations and nations since the 2004 Indian Ocean tsunami that killed 131,000 people in Indonesia's Aceh province alone.

"We are now reaching more and more victims,'' Jan Egeland told The Associated Press in Brussels, Belgium. "I am getting reports that we are making enormous progress.''

The government's Social Affairs Ministry said the official death toll rose Wednesday to 5,846.

Most survivors were still living in improvised shacks or group shelters erected in rice fields. Groups of families cooked together, each contributing scavenged food.

Despite government promises of aid, shortages of food and fresh water remained a pressing concern, and thousands of people used cardboard boxes to beg for cash and supplies from passing drivers.

The head of a Malaysia search and rescue team said hope had faded of finding more survivors or bodies, and his group had turned to clearing rubble from streets instead.

"The collapsed homes were all so small that anyone who was trapped would have been extracted by their family members,'' Abdul Aziz Ahmad said, adding his team found only one body Monday.

A 44-member team of Chinese doctors, search and rescue workers and seismologists also arrived with five tons of supplies, including a field hospital, China's official Xinhua News Agency reported.

Thailand said it would send 48 military medical personnel, medicine and equipment.

Teams from Malaysia, Singapore, Norway and other nations already are working in the area.

The Asian Development Bank announced a total of $60 million in grants and low-interest loans to rebuild the earthquake zone.

President Susilo Bambang Yudhoyono, who has temporarily moved his office to Yogyakarta and spent a night sleeping in a tent with survivors, vowed to fight corruption in delivering aid money.

"I am ordering that not even one dollar will be misused,'' he said.

The quake was the fourth destructive temblor to hit Indonesia in the past 17 months, including the one that triggered the Dec. 26, 2004, Indian Ocean tsunami.