Michael Elmquist said that while American helicopters were speeding relief supplies to villages isolated by the Dec. 26 disaster, their crews were not spending enough time on the ground to assess survivors' needs.
"They don't stop their engines. They're on the ground for five minutes," Elmquist told reporters in the provincial capital of Banda Aceh, on the hard-hit northern tip of Sumatra.
U.N. Secretary General Kofi Annan urged world leaders at an international tsunami aid conference in Jakarta to immediately come forward with $1 billion of the nearly $4 billion in aid they've promised.
The United Nations has warned some of the promises might not be honored, as has happened in the past.
Secretary of State Colin Powell said the four-nation coordination between the United States, Australia, India and Japan announced by President Bush was now being disbanded and instead folded into the broader U.N. effort, reports CBS News Correspondent Lee Cowan.
The U.S. relief operation on Sumatra has won praise for reaching villages devastated by the earthquake and tsunami, which washed out roads and destroyed bridges. But Elmquist said he couldn't be sure what the U.S. helicopters were delivering.
"I don't know what they had on board," Elmquist said. "We don't get any feedback."
The United Nations has only had "brief contact" with the American military, Elmquist said, adding that he would "like to see it intensified over the next few days."
Bureaucracy has also stalled efforts.
The United Nations had arranged to send experts on helicopter assessment missions Thursday to villages near the flattened coastal city of Meulaboh. However, when they reported to Banda Aceh airport, they were turned away because of paperwork, Elmquist said.
Elmquist said it was a shame that critical humanitarian needs were slowed by red tape.
"I do feel a bit frustrated," he said.
Indonesia's Welfare Minister Alwi Shihab, who was seated beside Elmquist at a press briefing, sought to downplay the mix-up.
"No big deal. It's only a 24-hour delay," he said.
Meanwhile, American helicopters from the aircraft carrier Abraham Lincoln picked up their pace Thursday, delivering 84,300 pounds of aid supplies — up from 14,000 pounds two days ago.
One of the pilots, Cmdr. Mike Horan, of Mountain View, California, navigated through mist and drizzle, flying low under dark monsoon clouds.
His Seahawk chopper carried water, bags of rice, cartons of condensed milk and children's toys to Kuede Teunom, a 100-mile stretch down the devastated coastline from Banda Aceh. Some 8,000 of the coastal town's 18,000 residents are believed to have perished.
The United Nations estimates that some 800,000 people on worst-hit Sumatra are in need of emergency help, with many people still not receiving aid.
Sen. Bill Frist, R-Tenn., a medical doctor and Sen. Mary Landrieu, D-Louisiana, visited tsunami-stricken southern Sri Lanka on Thursday, tying up two of the five U.S. Military helicopters presently available, reports CBS News Correspondent Allen Pizzey.
Relief efforts in Sri Lanka are focused on areas still cut off by both the tsunami and monsoon rains. The anticipated arrival of more U.S. helicopters and the Marines will do much to help get much need aid where it is needed the most, reports Pizzey.
A group of homeless men at the camp expressed frustration with government-led relief efforts, complaining that the local Red Cross had only set up their clinic, complete with flags and banners, a few hours before the U.S. senators visited. Red Cross officials said their mobile clinics were treating patients at hundreds of camps.
Just before his helicopter lifted off, Frist and aides took snapshots of each other near a pile of tsunami debris.
"Get some devastation in the back," Frist told a photographer.
In Sri Lanka, Muslim bakers donated bread and grocers gave food to survivors at a school in Valaichchenai village being used by Hindus left homeless — an example of ethnic divisions in this civil-war torn country being put aside in the disaster's aftermath.
Individual donations are making a big difference in the private aid collected in the United States. American Red Cross president Marty Evans tells CBS Early Show co-anchor Harry Smith that individuals gave 60 percent of the roughly $100 million raised so far. The rest is from corporations.
Potentially deadly infections are sneaking into superficial wounds, said Dr. Ronald Waldman, who is coordinating WHO efforts in Indonesia.
Four of the nine patients who went through surgery at the Banda Aceh military hospital on Wednesday had legs amputated because of infections, the New York Times reports.
Pneumonia has also emerged as a significant illness, caused by exposure to dirty water during the tsunami.
But the number of cases of children with severe diarrhea is still low, Waldman said.
U.S. officials are tracking down 2,600 Americans who have been reported missing in the wake of the Dec. 26 tsunami, Ambassador Maura Harty told CBS News Early Show co-anchor Hannah Storm.
She said there are 18 presumed American deaths between Thailand and Sri Lanka. A high ranking state department official speaking on the condition of confidentiality put that figure at 36 on Wednesday.
In the past six days, at least four shootings have prevented aid workers from helping hundreds of refugees, said Sgt. Muhammad Guntur of Indonesia's elite Kopassus forces.
Guntur accused rebels from the Free Aceh Movement of disrupting the distribution of aid.
An Associated Press reporter witnessed one incident of gunfire on a relief camp in Lhoknga.
In another possible danger to aid workers, some radical Islamic groups are sending men into Aceh - perhaps to stir up sentiment against U.S. and Australian troops there, a terrorism expert said.
"They appear to see their role not only as helping victims but as guarding against 'kafir' - infidel - influence," said Sidney Jones, Southeast Asia project director for the International Crisis Group.