"There has been an improvement, but it is not good enough," Brown said. "It is not good enough because the Burmese people are 1.5 million people who face famine or distress, and it's not good enough because the regime is still preventing aid getting to the rest of the country."
The country's junta told visiting Thai Prime Minister Samak Sundaravej that it is in control of the relief operations and doesn't need foreign experts.
Samak visited a government relief center in Yangon and told reporters after returning to Bangkok that the junta has given him the "guarantee" that there are no disease outbreaks and no starvation among the cyclone survivors, according to The Associated Press.
The U.N. and relief agencies inside Myanmar said that aid has reached only 270,000 of the estimated 1.5 million who need food, water and medical care.
International agencies say the lack of roads, lack of equipment, bureaucratic bottlenecks and Myanmar's refusal to accept help have left most survivors hungry, thirsty and shivering in the rain.
The planes that have landed have brought in high-energy biscuits, sheeting and tents, drinking water and water-purification tablets, as well as boats to reach survivors in the flooded areas and heavy lifting equipment to speed the unloading of additional planes.
Eight planes from the United States have now landed in the capital of Yangon to deliver supplies.
In Washington, the State Department renewed appeals for the junta to allow outside disaster relief experts and more aid into the country.
"We want to see the regime do more to allow the outside world to be able to help people in need in that country," deputy spokesman Tom Casey said. "This is not a political issue, this really is simply a humanitarian issue."
The Associated Press and Reuters contributed to this report.
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