The UN is preparing to send two planeloads of food and relief items to Burma on Saturday to provide aid in the aftermath of the cyclone that has killed tens of thousands.
UN Secretary General Ban Ki-moon made the announcement as Burma's military leaders seized aid shipments headed for cyclone survivors and told the top US diplomat there they are not ready to allow American aid workers into the country.
Mr Ban said he has received reports from his staff that conversations had begun with Burmese officials to break the gridlock, although he said leaders of the military junta had "regrettably" not yet made direct contact with him. "It's moving toward the right direction," he said.
Bush administration officials said Burma's governing military junta has agreed to allow a single US cargo aircraft to bring in relief supplies for victims of the devastating cyclone.
White House spokesman Gordon Johndroe said the United States welcomed the go-ahead to land a US military C-130 in the country on Monday. The breakthrough came after days of waiting on the US side.
The UN planes are set to arrive in the country on Saturday, Mr Ban said at a global health conference during a visit to Atlanta. At the meeting, which also included former US president Jimmy Carter, Mr Ban again pressured Burma's leaders to grant visas to aid workers to enter the country.
"I appeal to them strongly to do all they can to facilitate this aid," Mr Ban said. "We must put aside all political differences."
He also urged the junta to postpone indefinitely a constitutional referendum scheduled for May 24.
"While respecting the sovereign decision of the Myanmese government, I thought it would be prudent for the Myanmese government to focus and concentrate their very limited resources and time and energy on saving the lives and reconstruct the country," he said. "Then I think we can do a referendum at a later date."
Officials have said that up to 1.9 million people are homeless, injured or threatened by disease and hunger. Another 4 inches of rain was forecast to fall next week. Diplomats and aid groups warned the number of dead could eventually exceed 100,000 because of illnesses and said thousands of children may have been orphaned.
