The famine in Cambodia is subsiding after nearly a year, and as it does, provincial authorities and western relief experts are discovering that far more of the population survived than had been generally believed.

These observers now believe that as many as 6 million Cambodians remain alive today. Last summer, the Vietnamese-installed regime in Phnom Penh claimed that about 3 million of the country's 7 million inhabitants had died in the famine and the bloody years of the Pol Pot regime.

Easing of the famine is credited to food aid from the Soviet bloc, Vietnam and a few Western charities, and to a lesser extend to food cached in the countryside by the Cambodians themselves. In addition, the Phnom Penh govermnet of Henng Samrin is new permitting the distribution of about 50,000 tons of internationally supplied food.

These measures, along with a modest winter harvest and the massive Western food program along the Thai-Cambodian border, have convinced relief experts that most of the people will be able to hang on for the next few months. Famine could recur in late spring, however, unless massive additional aid shipments are forthcoming.

The new population figures, which are similar to a CIA estimate reported late last year, are based on as as-yet-unpublished survey by Heng Samrin's own provincial officials. The government, in order to allocate the aid now pouring into the country, ordered each provincial chief to count the people in his territory. Taken together, these counts revealed a national total of more than 6 million.

"Apparently, these are accurate figures," said a foreign relief expert who asked for anonymity. "Everyone' hesitant to talk about it because the Kampuchean [Cambodian] authorities don't want it out. They consider it strategic information or something."

David Elder, the Southeast Asia program coordinator for the American Friends Service Committee, was recently returned from Cambodia, said that local authorities told him of the population survey, but that he believes its total was "bloated."

Nonetheless, relief officials are now recalculating the amount of food aid needed for Cambodia this year -- over 200,000 tons -- on the basis of these new population assessments. Allowing for inflation by the Cambodians, these officials put the country's population at between 5.5 million and 6 million.

Western experts speculate that the new population figures have been withheld by the Heng Samrin regime because they conflict with the official government position.

Last summer, Heng Samrin accused the deposed Pol Pot of causing the deaths of 3 million Cambodians, and issued desperate appeals to the United Nations and the world at large. These appeals brought steadily increasing amounts of aid from around the globe.

At the same time, the question remains: To what extend is a real recovery under way?

"This could be a plateau," suggested one aid official in New York. "The weak have died or become refugees in Thailand. The abject conditions of the refugees this fall were not cosmetic nor was the horrible condition of the orphans in Phnom Penh. What we don't know is how many more are hidden from our view, in the hills and the out-of-the-way spots in Cambodia."

In other words, the recovery of Cambodia may be temporary and the cycle could easily turn for the worse by March. "Can they hold up if the food supply dwindles again and there isn't enough medical treatment available" the official asked.

Some aid experts speculate that Phnom Penh is holding its best stock -- the international rice -- for just such an emergency during the spring months ahead. "We still have seen nothing to believe we overestimated the famine," said an American government official charged with overseeing the Cambodian situation. "This is a war situation as well as a famine situation . . . visitors are taken to areas where the lives of the people have improved, dramatically in some cases. It is part of a drive to show that the Heng Samrin authorities are reviving the country and are worthy of official recognition."

Throughout this fall and winter, politics has jeopardized attempts to feed Cambodia.

Despite claims to the contrary, it appears that all the interested nations and relief organizations contributed in some way to the revival of the nation. The Soviet Union, for instance, shipped 40,000 tons of red corn.

But when and how these countries and groups helped was dictated by their concern -- and Heng Samrin's -- over which foreigners would get credit for "saving" Cambodia.

At its peak the western and international aid effort on the Thai-Cambodian border fed over a million Cambodians in refugee camps and the interior of Cambodia. Peasants trekked to border feeding stations -- "a human land bridge," as one relief officer put it -- and carried back rice to the starving in western Cambodia. Some of the rice eventually showed up on the black market in Phnom Penh.

But except for some small quantities of aid from private charities, the West was not responsible for the recovery of the country itself last year.

Heng Samrin was openly suspicious of western and international aid and, until a few weeks ago, allowed over 50,000 tons of high-grade rice from the Unicef-Red Cross joint mission to stockpile in his country's warehouses. He was content to distribute and from Vietnam and the Soviet Union first and credit them with reviving Cambodia, and to blame the West, as well as the deposed Pol Pot, for the country's ills.

In January, western shipments were cut back until an agreement was reached whereby Heng Samrin began to distribute international aid -- which he did, dispatching about 11,000 tons of rice -- and the international community agreed to bring in some 200,000 tons of food to Cambodia this year.

When aid officials first visited Cambodia last summer, almost nothing worked in the country. Under four years of Pol Pot's harsh social experimennts, the country was pushed back to an almost medieval state and the people were traumatized by his tyranny. During the Vietnamese invasion, roads, the seaport and other strategic points were damaged by the contesting armies.

At first international officials blamed this dismal infrastructure and the small, inexperienced Heng Samrin bureaucracy for the inability to dispatch their aid around the country.

Once these aid group realized, however, that politics also was blocking aid distribution, they exerted-pressure through their own representatives and the international communityies to convince Cambodian authorities to give out the food.

Heng Samrin officials not only are trying to convince Cambodians that they are responsible for saving the country. They want the international community to believe this as well; At last fall's United Nations General Assembly, Heng Samrin lost badly to Pol Pot officials who were reseated as the recognixed government of Cambodia in protest against the Vietnamese occupation. The General Assembly, also adopted a resolution calling on all foreign troops to withdraw from Cambodia. Vietnam's occupying force is some 200,000 strong.

Now, with Britain's move to derecognize Pol Pot and Indian Prime Minister Indira Gandhi's campaign pledge to recognize Heng Samrin, the political prospects of the Phnom Penh authorities are looking up, according to some experts.

"While the world's attention has been focused on Iran and Afghanistan, the Vietnamese and Heng Samrin have been mounting a nice campaign to improve their immage," said an international aid official."They now seem confident enough to cooperate with us."