By Jonathan Head
BBC News, Bangkok
A third of young children in Burma are chronically malnourished, and large numbers receive little or no education, the UN's World Food Programme has said.
Government controls are stopping goods moving freely, the WFP says
WFP executive director James Morris said government restrictions on the movement of goods and people were holding back economic development.
He urged Burma's military rulers to allow humanitarian agencies more freedom to offer assistance.
He was speaking after a four day visit to the country.
Mr Morris was the first senior UN official allowed to visit Burma in more than a year, as prospects for political reform have faded.
He painted a grim picture of the humanitarian situation inside the country.
Around a third of children under five are chronically malnourished, he said.
In some border areas, where the army is fighting ethnic rebels, the figure rises to 60%.
Just as worrying for the country's future, he said, were the large numbers dropping out of school at an early age.
Mr Morris said the government's policy of trying to control the economy and the movement of people was to blame for the fact that so much of the population cannot feed itself, despite Burma producing a surplus of rice last year.
"I'm suggesting that the government would be well-advised to make it easier for people to move about, to buy and sell agricultural commodities, without so many check-points, without economic interference from the government," he said.
Like other humanitarian agencies in Burma, the WFP is careful to avoid calling for political reform.
But Mr Morris did appeal for fewer restrictions on the activities of his staff there.
Food aid bought by the WFP is being taxed by the government and the convoluted system of authorisation by local military commanders makes it almost impossible to move food supplies from one part of the country to another.