Vietnam has strong reasons to hold on to Kampuchea, despite military and economic burdens

For Vietnam, the political, economic and security reasons for continuing the more than three year old occupation of Kampuchea outweigh considerable economic disadvantages.

This is why Hanoi appears to have no intention of withdrawing its army from its small Asian neighbor despite intense pressure from China, the United States, and the Association of Southeast Asian Nations (ASEAN), according to analysts here.

Thus the current flurry of diplomatic activity aimed at seeking a political solution to the question of Kampuchea (Cambodia) seems unlikely to break the present deadlock.

The United Nations General Assembly has three times unsuccessfully demanded that Vietnam withdraw its troops from Kampuchea. Vietnam has refused even though its economy is hurting, partly because it has to divest resources from domestic uses to support its military presence in Kampuchea.

Vietnam has offered to withdraw its troops from Kampuchea if Thailand withdraws its support from pro-China Khmer Rouge guerrillas and if China ''stops being hostile'' toward Vietnam.

In the latest diplomatic rounds, Vietnam's foreign minister Ngyen Co Tach is expected to visit France, Sweden and other European countries next month. UN Secretary General Perez de Cuellar is about to send Refeuddin Ahmed, his special representative for humanitarian affairs in Southeast Asia, to Bangkok, Singapore , Kuala Lumpur, Manila, Jakarta, Vientiane, Hanoi, Peking, Tokyo, and possibly Moscow in an exploratory bid.

Several foreign ministers from the ASEAN countries (Thailand, Singapore, Malaysia, Indonesia, and the Philippines) have recently visited Peking. ''But all these past and future meetings amount to no more than to a dialogue of the deaf,'' says one informed Asian ambassador.

''China's commitment to the Khmer Rouge (ousted by Vietnam after holding power from 1975 to 1979) only strengthens Vietnam's resolve to stay there,'' according to a high Western official who has kept in close touch with the situation. This official and other senior diplomats who have been involved in seeking a political solution to the Kampuchean question, see these factors behind Vietnam's insistence on maintaining dominance in Kampuchea and in Laos:

* For security. Hanoi sees these countries as buffer states much in the way the East European countries are supposed to shield the USSR's western flank.

* For a food supply. Kampuchea in particular is destined in Vietnam's view to be its rice granary. Vietnamese diplomats stress the fact that the ''solidarity'' of the free Indochinese people is irreversible, a polite way of saying that Indochina is historically Vietnam's sphere of influence.

The three anti-Vietnam Kampuchean factions (the Khmer Rouge, estimated strength at least 35,000 men led by Khieu Sampan, the Khmer People National Liberation Front, some 9,000 men led by Son Sann, a prime minister under Prince Sihanouk, and Sihanouk himself with up to 3,000 men) have been unable to form a tripartite government or even a loose coalition. Each group fears it will be simply used and later discarded by the others. Distrust between them runs very deep, according to reliable sources.

With the possible exception of Thailand, the ASEAN countries are increasingly uncomfortable backing the Khmer Rouge, whose widespread killings while holding power from 1975 to 1979 have made them unpopular in Kampuchea. The ASEAN countries would like to broaden the Cambodian resistance and raise to greater prominence more credible leaders such as Sihanouk and Son Sann.

However China has reportedly refused to exert pressure on the Khmer Rouge to induce it to agree to the conditions set by rival Kampuchean groups for forming a coalition.

Malaysia's prime minister Dr. Mahathir Mohamad has recently spoken of withdrawing ASEAN backing for the Khmer Rouge as holder of Kampuchea's United Nations seat, if the communist organization doesn't mend its ways.

Meanwhile the superpowers seem not particularly unhappy with the present stalemate and are not actively pressing for a solution. According to diplomats close to the scene:

* China finds the present situation advantageous since it allows it to ''bleed'' the Vietnamese through the Khmer Rouge guerrillas and since it obliges the ASEAN countries, who fear Vietnam's war machine, to line up closer to China.

* The Soviet Union, whose assistance is desperately needed by Vietnam, now outflanks China with its navy enjoying the port facilities of Cam Ran Bay and easier access to the Indian Ocean.

* The United States shares China's opposition to Vietnam's invasion of Kampuchea. But it is also sympathetic to ASEAN's desire for a broadened anti-Vietnamese resistance coalition and shares ASEAN's desire for a settlement that does not ''bleed Vietnam into the ground.''

This ''straddling of the fence'' posture has led to charges that Washington does not have a clearly defined Southeast Asia policy and is content to leave the field to China.