YANGON, Myanmar - U.N. Secretary-General Ban Ki-moon urged Myanmar to focus on saving lives, not on politics, after the military government on Wednesday shunned a U.S. proposal for naval ships to deliver aid to cyclone survivors.

The U.N. says up to 2.5 million survivors of Cyclone Nargis face hunger, homelessness and potential outbreaks of deadly diseases.

"We must do our utmost for the people of Myanmar" Ban told reporters after arriving in Bangkok, Thailand. "The issues of assistance and aid in Myanmar should not be politicized. Our focus now is on saving lives."

Ban was to fly Thursday to Myanmar on a mission to scale up relief efforts and lobby the junta to allow more foreign aid workers into the isolated country. He told reporters his two-day visit would include a trip to areas devastated by the cyclone and talks with officials, including junta leader Senior Gen. Than Shwe.

Before leaving U.N. headquarters, Ban said the world body had finally received permission from the junta to use helicopters to carry aid to stranded victims.

His announcement was not immediately confirmed by officials in Myanmar.

Myanmar's state-controlled media said that U.S. helicopters or naval ships were not welcome to join the relief effort.

The New Light of Myanmar newspaper said accepting military assistance "comes with strings attached" that are "not acceptable to the people of Myanmar."

The report cited fears of an American invasion aimed at grabbing the country's oil reserves.

The United States, as well as France and Great Britain, have naval vessels loaded with humanitarian supplies off the Myanmar coast, waiting for approval from the junta. The article did not say whether the French and British supplies would be allowed.

The four U.S. warships in the region were seen as a major potential boost for the relief effort with the capacity to deliver supplies to inaccessible areas of the low-lying Irrawaddy delta, with 14 helicopters, two landing craft vessels, two high-tech amphibious hovercraft and about 1,000 Marines.

American military aircraft are already sending aid on about five flights a day from Thailand to Yangon.

The New Light of Myanmar gave no explanation why the regime was willing to accept aid flown on U.S. C-130 cargo planes, with U.S. military personnel on board, but would not allow the warships and helicopters to deliver relief supplies.

Myanmar's xenophobic leaders appear to have long feared an invasion by the United States, a concern that some analysts believe prompted the junta's abrupt decision in 2005 to move the capital from Yangon to the remote city of Naypyitaw, which is equipped with bunkers.

Before leaving New York, Ban welcomed the junta's "recent flexibility" in saying it will allow relief workers from the 10-country Association of Southeast Asian Nations — of which Myanmar is a member — to begin distributing aid.

He warned that relief efforts to save cyclone survivors had reached a "critical moment."

"We have a functioning relief program in place but so far have been able to reach only 25 percent of Myanmar's people in need," he said Tuesday.

So far, the few foreign aid workers allowed inside the country have been banned from the areas of the worst devastation in the delta.

At least 78,000 people were killed in the May 2-3 storm and 56,000 remain missing. European Union nations have warned that Myanmar's junta could be committing a crime against humanity by blocking aid.

Ban also planned to attend a meeting of aid donors in Yangon on Sunday. Myanmar, one of the world's poorest nations, claims losses from the disaster exceeded $10 billion.

Myanmar's leaders began three days of mourning for the dead and missing Tuesday.