However, the diplomatic wheels are starting to turn, raising hopes that experts adept at establishing networks to distribute aid may finally be able to help.
At an emergency disaster response meeting in Singapore on Monday, the Association of South East Asian Nations of which Myanmar is a member, said it would coordinate the aid effort and set up a "mechanism" for more supplies.
United Nations Secretary-General Ban Ki-moon is also set to fly in on Wednesday to try to convince the generals it is in their interests to open up and put aside pride and paranoia.
"His objective is to reinforce the ongoing aid operation, see how the international relief and rehabilitation effort can be scaled up and work with Myanmar authorities to significantly increase the amount of aid," his spokeswoman Michele Montas said.
Details of ASEAN's plan and its relief "task force" are still sketchy, although the 10-nation group and the United Nations announced in a joint statement that they would convene a donor conference in Yangon on May 25.
Myanmar had also agreed to accept nearly 300 medical personnel from its neighbors to supplement the few outside teams of doctors already admitted, ASEAN said.
"We have to look at specific needs. There will not be uncontrolled access," Singapore Foreign Minister George Yeo said.
The U.N.'s chief humanitarian officer, John Holmes, is expected to meet Prime Minister Thein Sein on Tuesday to deliver a message from Ban to the generals. Holmes visited the devastated delta towns of Labutta and Bogalay on Monday.
While aid has been trickling into the delta, the World Food Programme says it has managed to get rice, beans and biscuits to just 250,000 of the 750,000 people it thinks are most in need.
Britain's Asia minister Mark Malloch-Brown said after returning from Myanmar that the generals and aid groups had widely differing views as to immediate priorities.
"Getting a needs assessment done in time for the donors' meeting is critical to get everyone on the same page," he told reporters in London.
In one town in the upper delta, a steady stream of refugees arrived after travelling for days from Pyinsalu, one of the worst-hit districts.
"I didn't have any kids, but I lost all my relatives. It's only my wife and me now," said one man, his clothes soaked by rain and wearing no shoes.
In the last 50 years, only two Asian cyclones have exceeded the human toll of Nargis -- a 1970 storm that killed 500,000 people in neighboring Bangladesh and another that killed 143,000 people in 1991, also in Bangladesh.