SITE 2 REFUGEE CAMP, THAILAND -- Fleeing west to guerrilla camps or east to government areas, about 150,000 Cambodians have been driven from their villages this past year by war, hunger and disease.

Many of those reaching the O'trao refugee camp just inside Thailand "are just one step better than the people in concentration camps during World War II, and that's no exaggeration," said a Western aid official.

"They're coughing, they have open wounds. It seems like everything that could possibly go wrong with the human body has gone wrong," he said, speaking on condition of anonymity. "They are sent right to the hospital and admitted."

Western officials say the influx of refugees in the camps is one of the largest since 1979, just after Vietnam invaded Cambodia and ousted the murderous Khmer Rouge.

Many of the new refugees have malaria, a disease that has seen a dramatic surge at camp hospitals.

In the past year, U.N. officials said, 20,000 to 30,000 Cambodians have fled west to six crowded camps along the Thai frontier.

U.N. officials said another 130,000 people were displaced inside Cambodia in 1990,, the first major internal displacements in the war.

Many of those refugees are in dire need, and efforts to deliver food have been hampered by the country's battered infrastructure and shortages of trucks and fuel. The United Nations has appealed for more emergency food aid.

The camps, now with 300,000 refugees, get U.N. food and medical and other services and are much better off than villages inside Cambodia. They are controlled by three guerrilla groups fighting the Vietnamese-installed government.

Many of the refugees fled the fighting when it spread after the Vietnamese troop pullout in September 1989, which allowed the guerrillas to make unprecedented gains in many areas outside their traditional bases bordering Thailand. The pullout also cleared roadblocks and other barriers for people trying to reach the frontier.

Large numbers also fled the stepped-up government draft. Others have gone to the camps for medical treatment, to join relatives or to escape poverty.

"They say they don't want to go back before a peace settlement," an aid official said of the refugees. "Most are farmers. Many come with their whole villages where there was fighting."

Many more may come. The dry season fighting is starting, and Cambodia faces serious food shortages in 1991 because many rice fields could not be planted due to fighting, floods or drought.

Aid officials said many of the new arrivals at O'trao and Site K camps in Thailand are among the 60,000 to 100,000 people from "hidden" Khmer Rouge camps that were moved from Thailand into Cambodia last year.

Many returned west to the U.N. camps because of disease and hunger in the Khmer Rouge settlements. In letting many refugees resettle in the U.N. camps, the guerrillas appear to have relaxed their once-tight grip. U.N. officials were not allowed to enter the hidden camps.

The vast majority of the new refugees have gone to the huge Site 2 camp run by the non-Communist Khmer People's National Liberation Front. Many Cambodians have relatives among the 180,000 people in the camp, known as a place to live freely and to make money.

Site 2 administrators say thousands more would come if they could afford the guerrillas' "tax" for passing through zones fronting the camp.

Most of the refugees are from western provinces bordering Thailand. Some are from as far away as Takeo and Prey Veng provinces bordering southern Vietnam.

Phach Sep, 57, came to Site 8 from Takeo to join a son from whom she had been separated for 18 years by war. A driver took pity on the tiny woman and drove her to the border area. Then she walked three days through the jungle.

Rim Thong, 44, reached Site B camp north of Site 2 with his 11-member family and all 68 families of their hungry village. He could not grow rice after his two cattle were killed by land mines. Fighting was worse than last year, and there were daily clashes because his village was near a government military camp.

"Here there is no need to prepare to escape from the fighting," Rim Thong said.