YANGON, Myanmar, May 14 (UPI) -- U.S. airlift of aid to cyclone victims in isolated Myanmar entered the third day but the United Nations said the ruling junta is limiting access to them.

Two U.S. military planes loaded with supplies, including drinking water, landed Wednesday in the former capital Yangon. The first flight arrived Monday following strenuous international protests against the junta's tight grip on the country formerly known as Burma.

Three more flights were to follow Wednesday, Xinhua reported.

The U.N. Office for the Coordination of Humanitarian Affairs warned unless more access is granted to allow aid to flow more quickly, another catastrophe from infections and other risks could result, the U.N. News Center reported.

Despite some progress in the relief effort, OCHA spokeswoman Elizabeth Byrs said the United Nations and its partners have been able to reach about 270,000 of the 1.5 million survivors 12 days after the storm.