UNITED NATIONS (CNN) -- Myanmar's reclusive government has agreed to allow U.N. helicopters into some of the least accessible areas of the country's cyclone-devastated delta, U.N. Secretary-General Ban Ki-moon said Tuesday.
Little aid has reached victims of Myanmar's cyclone as flooding continues.
The military junta has limited access by other nations and aid organizations -- for the most part, allowing them only to drop off supplies at the Yangon airport.
The United Nations World Food Programme and the International Red Cross were among the first to have workers in the country, but their movement has been limited.
The World Bank announced Tuesday that it will support U.N and ASEAN efforts to get access to the disaster areas. The World Bank has not received requests from Myanmar's junta for financial assistance, the group said in a written statement.
"This is a critical moment for Myanmar," said Ban, who plans to visit Myanmar on Wednesday. "We have a functioning program in place, but so far we have only been able to reach about 25 percent of Myanmar's people in need." Watch Ban as he heads to Myanmar »
Nine U.N. helicopters will be allowed into the country, he said.
Ban said he is confident the government will now expedite the issuance of visas, the lack of which has kept most aid workers out of the country.
Myanmar's leaders agreed Monday to let its South Asian neighbors send medical personnel and an assessment team to the devastated region, more than two weeks after a storm that killed tens of thousands of people.
Ban will tour the cyclone destruction in the Irrawaddy Delta and confer with Myanmar's leaders, he said. Watch how the food supply stream was wiped out »
He said he wants to "see for myself" the unprecedented destruction, meet with U.N. staff stationed in the area, and reassure himself that aid efforts are well-coordinated.
"I will do my utmost for the people of Myanmar," he said.
On Sunday, the Association of Southeast Asian Nations and the United Nations are hosting a conference in Yangon on disaster relief and other topics.
An ASEAN assessment team will travel to Myanmar on Wednesday to gauge the impact of the disaster and the scope of aid needed.
"I'm encouraged that ASEAN leaders have taken a leadership role," Ban said.
He is to return to New York on Monday.