Refugees from Cambodia's western provinces say grain being shipped to the famine-racked nation by international agencies is not reaching their villages.

Under an accelerated schedule, international agencies unloaded 25,000 tons of grain at the Cambodian port of Kompong Som during the past two months and plan to ship 30,000 tons in December alone.

But, said one refugee, a 46-year-old former professor of literature, "I never saw any of it. All we got was a tiny bit of corn."

He and other Cambodians said in interviews that malnutrition was killing off people in the country's interior. The search for food will continue to bring waves of refugees to Thailand, they predicted, even though Vietnamese troops backing the Heng Samrin government shoot at people they catch on the move.

Stories like this can be heard in countless variations in Camp 204, a sprawling city of thatch huts that is home for a third of the more than 600,000 Cambodians who have reached the frontier in recent months.

Refugees arriving here also say that Vietnamese troops stationed in Barambang Province are making the food shortage worse by preventing farmers from harvesting what little rice they have grown this season. The soldiers were quoted as saying the grain must be allowed to turn brown on the stalk and be gathered later as seed.

Farmers in one district were told that "friendly socialist countries" would provide food until next year's harvest. (Soviet bloc countries are reported to have supplied 124,000 tons of food to Cambodia.) But to date the only food to arrive is the kind of corn normally used as animal feed, many refugees said.

The former professor said that in his village, Koke Pheung, a community of 500, the soldiers gave each person only 200 grams (about seven ounces) of corn a month. "That's not even enough for one meal," he remarked bitterly.

Earlier this month, with food stocks in the village so low that old people were dying, he decided to try to reach Thailand. He joined with about 50 other people and followed the jungle trails to the frontier about 60 miles away. They were lucky; no Vietnamese patrols spotted them, he said.

Many rufugees are convinced the Vietnamese are holding the rice back to starve the Cambodian people into extinction. Others see food as a political lever. It is withheld from areas where guerrillas loyal to the ousted Khmer Rouge government operate. Or it is used to reward soldiers and civilians who take posts with the Heng Sarin government, with the remainder going to feed Vietnam itself.

Officials at the U.N. Children's Fund (UNICEF) and the International Red Cross, the two agencies coordinating relief efforts into Cambodia, generally point to logistical problems in moving rice around a country that is virtually without trucks, railways and unloading equipment.

Commenting on proposals to truck in huge quantities of rice directly from Thailand, one official noted: "That's a really good idea but when you look at the roads you see they simply can't handle 10-ton trucks."

Logistical constraints dictate that the distribution close to Phnom Penh and Kompong Som will be better than that in remote provinces, it is argued. People well fed by the foreign supplies would not be likely to turn up in Thai refugee camps to tell the tale.

Still, they concede that the limited foreign staff the Heng Samrin Government has allowed into Phnom Penh must do its best to upgrade monitoring of distribution. UNICEF officers in Geneva recently took public note of this concern: "We know the food is arriving in Dampuchea [Cambodia]. But very little is getting to the population," a spokesman was quoted as saying.

Reguees agree and often smile in consternation when reporters ask if any rice reached them. People recall the threat of starvation acutely and most everyone in Camp 204 can recite the rice ration in his home village -- how many people share a soup can sized container of rice per meal or per day.

They seem particularly incensed over the orders against harvesting. However, agricultrual specialsists here feel that order could be part of a calculated if brutal effort to assure a more normal harvest next year.

To serve as seed, rice grains must be allowed to grow to full maturity. Rice cut prematurely, as Cambodian farmers would be tempted to do to alleviate food shortages, would be useless as seed, a rice specialist here said. Given the adverse conditions on Cambodian farms, which lack fertilizer and draft animals, for instance, and the fact that only a fraction of normal acreage was planted this year, farmers could conceivably need this year's entire crop as seed for next year.

However, huge numbers of farmers will not be present for next spring's planting. Despite the risks, they are continuing to uproot their families and trek to Thailand. Newly arrived refugees say the trails are at times literally jammed with people.

The walk takes patience as well as courage. The former professor said: "The Viets close off a road one day, then the next day they're too lazy. If people can't get through one way then they try another."

Sometimes death stalks the trails. One man told of leaving Mongkol Borey district of Battambang with his wife, two children and about 200 other people. Close to the Thai border in the dead of night they ran into Vietnamese soldiers, who fired rocket-propelled grenades at them from only 50 yards. Two people died and the rest fled into the jungle, he said.

Until late summer, the estimated 170,000 Vietnamese troops stationed in Cambodia allowed virtual freedom of movement. But as food stocks dwindled and more people left for Thailand they clamped down with force. Many Indochina-watchers in Bangkok feel the Heng Samrin government feared losing a large portion of its population to Thailand.