NAYPYITAW, Myanmar - Myanmar's ruling military junta said yesterday that it would let foreign aid workers and commercial ships help survivors in the cyclone-ravaged Irrawaddy Delta, but it refused to relent on accepting aid from U.S., French and British military ships.

The ships, almost within sight of the coast for more than a week, offer a huge potential boost to the aid effort because they have the capability to send helicopters to the hardest-to-reach regions.

The military regime told U.N. Secretary-General Ban Ki-moon yesterday that all aid workers would be let into the country as long as it was clear what they were doing and how long they would remain.

The Irrawaddy Delta, Myanmar's key rice-producing region, was decimated by Cyclone Nargis, but the junta has kept it off-limits to foreign aid workers.

An estimated 2.5 million people remain in severe need, threatened by disease, hunger, and exposure because of the loss of their homes. The United Nations says that only about 25 percent of survivors have received any kind of aid.

Official estimates put the death toll at 78,000, with an additional 56,000 missing. Myanmar has estimated the economic damage at $11 billion from the May 2-3 storm.

Under intense international pressure - and with an aid donors' meeting scheduled for tomorrow - Senior Gen. Than Shwe said he would allow the entrance of aid workers "regardless of nationality," Ban said.

Than Shwe refused to relent on the landing of the military ships.

According to Ban, the Myanmar leader "agreed that international aid could be delivered to Myanmar via civilian ships and small boats."

The United States, Britain and France all have warships off Myanmar's coast ready to help. But Myanmar's junta is nervous about any landings because it fears invasion or political interference. It moved its capital from Yangon, the largest city, to this town in the north in 2005 in part because of such fears.

The junta is also wary of the political and psychological consequences of its people witnessing an aid operation run efficiently by Western militaries, which they have long accused of trying to undermine the country and turn it into a neo-colony.

Patience with the junta has been wearing thin.

At the United Nations in New York, France said Thursday it would push for a resolution authorizing the delivery of aid to survivors "by all means necessary" if pressure from Ban and Myanmar's neighbors did not open the aid pipeline quickly.

Pentagon spokesman Bryan Whitman said yesterday that 50 U.S. C-130 transport plane flights have been permitted into Yangon, carrying more than 480 tons of supplies. They have not been allowed to fly directly to the delta.

Whitman said the ships - led by the USS Essex - would remain for days or weeks but would not linger for months waiting for permission to bring in aid.

"If the position of the Burmese government doesn't change, we will have to make a decision to reallocate those Navy assets," he said.

Ban, who returned to Bangkok yesterday, said that details on moving aid workers still needed to be worked out, and "implementation will be key." But he stressed he believed he had achieved a breakthrough.

"I believe they will keep and honor their commitment," Ban said.

U.S. officials were more cautious.

State Department spokesman Tom Casey welcomed Ban's announcement but said Washington was waiting to see action. "Seeing is believing," Casey said.

Aid agencies have said they are preparing barges, rubber boats and other craft to deliver aid once approval is given.

"While the pace of aid deliveries has increased in the past week, the entire relief effort is only scratching the surface of what is needed in a disaster of this scale," said Melissa Winkler, of the International Rescue Committee. "Limited access to cyclone survivors has been the largest obstacle."

Nearly three weeks after the storm, the U.N. Food and Agriculture Organization warned that hundreds of thousands of people had insufficient food, and prices for rice, cooking oil and other basics have doubled throughout Myanmar.

Only a "very narrow window of opportunity" remains to provide seeds and other material to farmers before the rice-planting season begins, the agency said.