YANGON, Myanmar (CNN) -- The death toll from the cyclone that ravaged the Irrawaddy delta in Myanmar may exceed 100,000, the senior U.S. diplomat in the military-ruled country said Wednesday.
"The information we are receiving indicates over 100,000 deaths," the U.S. Charge D'Affaires in Yangon, Shari Villarosa, said on a conference call.
The U.S. figure is almost five times more than the 22,000 the Myanmar government has estimated.
The U.S. estimate is based on data from an international non-governmental organization, Villarosa said without naming the group. She called the situation in Myanmar "more and more horrendous."
Villarosa also said about 95 percent of the buildings in the delta region were destroyed when Cyclone Nargis battered the area late Friday into Saturday.
Based on the same data, 70,000 people are missing in the Irrawaddy Delta, which has a population of nearly six million people, Villarosa said. The official Myanmar government figure for the missing is 41,000.
Little aid has reached the area since Nargis hit, and on Wednesday crowds of hungry survivors stormed reopened shops in the devastated Irrawaddy delta.
The United Nations urged the military junta to grant visas to international relief workers amid estimates of one million homeless.
A United Nations official said nearly 2,000 square miles (5,000 square km) of the hard-hit delta are still underwater.
Charity workers have gathered at Myanmar's embassy in Bangkok, Thailand, with vehicles, emergency food supplies and medicine, waiting for their visa requests to be approved.
"We need this to move much faster," said John Holmes, UN humanitarian chief, after reading a statement from Secretary-General Ban Ki-moon.
There were earlier reports of "civil unrest" in the worst-hit areas where people are scrambling for limited food supplies, a U.N. spokesman told CNN.
In the flood-soaked Irrawaddy delta townships, U.N. assessment teams observed "large crowds gathering around shops -- the few that were open -- literally fighting over the chance to buy what food was available," World Food Program spokesman Paul Risley said Wednesday from his office in Bangkok.
There were also also reports of price gouging in urban areas around Yangon, Myanmar's largest city and former capital.
"There were long lines of people trying to buy what food was available, even at those higher prices," Risley said.
The delta, Myanmar's rice-growing heartland, has been devastated by Cyclone Nargis, threatening long-term food shortages for survivors, experts said.
"We can't delay on this -- this is a huge disaster and the longer (Myanmar) waits the worse it's going to become," International Rescue Committee spokesman Gregory Beck said.
The Rome-based U.N. Food and Agriculture Organization (FAO) estimates that five states hit hardest by Saturday's cyclone produce 65 percent of the country's rice, The Associated Press reported.
"There is likely going to be incredible shortages in the next 18 to 24 months," Sean Turnell, an economist specializing in Myanmar at Australia's Macquarie University told AP.
Holmes said 24 countries had pledged financial support, with a total of $30 million expected in aid.
The WFP, which has started feeding the estimated one million homeless, said there were immediate concerns about salvaging harvested rice in the flooded Irrawaddy delta.
The cyclone battered the country with winds of 240kph (150mph) and 3.5 meter (11.48 feet) storm water surges.
Damage was also extensive in the country's largest city, Yangon. Much of the former capital is without power and littered with debris and fallen trees.
CNN's Dan Rivers, the first Western journalist into the devastated town of Bogalay, said Wednesday that it was difficult to find the words to describe the level of destruction.
"Ninety percent of the houses have been flattened... the help that these people are getting seems to be pretty much nonexistent from what we've seen."
He saw members of Myanmar's army clearing roads, but handing out little food or medicine.
"There has been scant help, really. I think we saw one or two Red Cross vehicles in the entire time we were driving," Rivers said of his travels over a 12-hour period.
Hundreds of World Vision staff are already in Myanmar with limited supplies, according to Bangkok spokesman James East.
Tons of supplies have been readied in Dubai and can be brought in quickly once clearance is given.
"Even when aid comes in, it's going to be a logistical nightmare to get it out to the remote delta region," East said.
However, Yangon is almost back to normal, World Vision health adviser Dr. Kyi Minn said. Roads have been cleared of debris, and electricity and potable water are available.
The Myanmar Red Cross has been handing out relief supplies, such as clean drinking water, plastic sheeting, clothing, insecticide-treated bed nets to help prevent malaria, and kitchen items, the International Federation of Red Cross and Red Crescent Societies said.
The United States has pledged $3.25 million and offered to send Navy ships to the region to help relief efforts -- if Myanmar's government agrees.
The U.S. military has flown six cargo helicopters onto a Thai airbase, as Washington awaits permission to go into the south Asian country, two senior military officials told CNN's Barbara Starr.
Other countries and world bodies including Britain, Japan, the European Union, China, India, Thailand, Australia, Canada and Bangladesh have also pitched in.
Based on a satellite map made available by the U.N., the storm's damage was concentrated over about a 30,000-square-kilometer area along the Andaman Sea and Gulf of Martaban coastlines, home to nearly a quarter of Myanmar's 57 million people.