Updated

Aid workers from the United States and around the world rushed tons of blankets, medicines and generators to Iran's (searchearthquake (search) survivors Wednesday, scrambling to prevent an outbreak of disease caused by dirty drinking water and cold weather.

A team of 80 U.S. medical specialists were setting up a field hospital in the devastated ancient city of Bam (search) and planned to begin treating patients later in the day. At least 12,000 people from this southeastern city were injured in Friday's devastating 6.6-magnitude quake that left at least 28,000 dead.

The U.S. team of 60 doctors and 20 logistical experts joins aid teams from more than 20 countries struggling to improve the harsh living conditions for tens of thousands left homeless by the magnitude-6.6 earthquake.

A top priority in the days ahead is to prevent the outbreak of typhoid or cholera — though there have been no reports of epidemics yet, said Marty Bahamonde, a spokesman for the U.S. delegation.

Bill Garvelink, the U.S. Agency for International Development official leading the team, met with several Iranian ministers after the team arrived Tuesday in what he said was probably the first official meetings between American and Iranian officials since Washington cut diplomatic links after the 1979 Iran hostage crisis.

"We don't focus on political issues," Garvelink said. President Mohammad Khatami thanked Washington on Tuesday but stressed that the aid did nothing to change frosty political ties.

However in a reflection of the political sensitivity of the U.S. presence in Iran, there is no plan to raise an American flag over the team's camp — though other foreign aid teams display a national flag, said Bahamonde.

Iranian health officials said they had all but given up hope of finding survivors buried under the rubble and focused on determining the medical and health needs of the city's remaining population, said Mohammad Nickam, a top Health Ministry official.

"There's no hope of finding people alive," Nickam said. The ministry has divided the city into 10 zones, each of which is under surveillance by health officials that were called in from neighboring provinces.

Meanwhile, aid continued to pour in from around the world.

An Australian air force plane carrying blankets, water purification tablets, and heaters unloaded the supplies in the provincial capital of Kerman, 120 miles northwest of Bam, according to an Australian defense official. The aid will be distributed by the Red Cross and Red Crescent aid groups.

China pledged $1.2 million in additional aid, doubling an earlier contribution of tents, generators and other supplies worth $600,000, the Chinese Foreign Ministry said on its Web site Tuesday.

Friday's earthquake struck before sunrise, entombing thousands of sleeping residents in their homes. The city's mud-brick houses, constructed without supporting metal or wooden beams, crumbled into small chunks and powdery dust.

Bam's 2,000 year-old citadel, the world's largest medieval mud fortress, was largely destroyed by the quake. The tallest section, including a distinctive square tower, crumbled like a sand castle.

Khatami said Tuesday a committee of foreign experts would determine how best to go about rebuilding the citadel.

"We will rebuild the Bam citadel as the symbol of some 3,000 years of history in this part of Iran," said Khatami, adding that the U.N. cultural agency, UNESCO, had offered to help. UNESCO had considered declaring the citadel a protected World Heritage Site.