President Samora Machel held an unusual "pot luck" dinner for the diplomatic representatives of the Big Five nations recently.

Each envoy brought something representing his country's culture. The American contribution was Lionel Hampton jazz tapes, the Chinese brought their cuisine and a chef to prepare it, while Britain, France and the Soviet Union provided scotch, champagne and vodka, respectively. Machel provided the country's specialty, giant prawns.

The strange three-hour "dinner of peace," however, was deadly serious for Mozambique, a southern African country whose people are among the world's poorest.

Machel asked East and West, which often pursue opposing policies in the area, to join in rescuing Mozambique from a hidden war that he believes is stage-managed by South Africa.

The expanding war against insurgents of the South African-supported Mozambique National Resistance (MNR) threatens to engulf the country's economy.

All of black-ruled southern Africa has a stake in the hostilities. The destabilization of Mozambique is dealing a serious setback to joint efforts by nine nations with more than 60 million population to develop their economies and end their reliance on South Africa, the white-minority-ruled powerhouse that they cannot live with or without.

For five of the countries, Mozambique's railways and ports provide the only alternative to routing imports and exports through South Africa.

Most of the attention in southern Africa is focused on the other side of the continent, where South African forces have occupied a chunk of Angola larger than Maryland for almost two years as part of the complex maneuvering over independence for Namibia, the last colony in Africa.

In Angola, the confrontation has all the brutality of modern warfare, employing jets, helicopters, tanks, missiles and long-range artillery.

On the Indian Ocean coast, however, the confrontation between black and white Africa across the Limpopo River frontier has a different quality. The struggle between Machel's Marxist government and the MNR is a hidden war that only surfaces occasionally in the overseas press when a foreign technician is kidnaped or vital oil storage facilities or railway lines are destroyed.

There are few set-piece battles and no front lines in the hidden war that now affects all but one of Mozambique's 10 provinces. The evidence is rather in the form of shot-up vehicles, burned-out stores and mutilated people with ears, lips or breasts cut off as the rebels pursue a policy of economic sabotage and instilling fear into the people, according to the Machel government.

In such hostilities, casualties are hard to measure. By standards of modern warfare they are low, perhaps fewer than 2,000 killed, but the toll is increasing rapidly. One western diplomat estimated that more than 500 combatants were killed last year, as well as many civilians.

More than two dozen foreigners have been kidnaped, some held for as long as eight months, and six Portuguese have been killed.

Machel is in no apparent danger of being overthrown, but the resistance has caused severe problems to a shaky economy already plagued by underdevelopment, drought and mismanagement. Travel is dangerous in many parts of the country, and distribution of consumer goods has been disrupted.

The MNR, which is believed to have about 10,000 guerrillas in the country, has not proclaimed any specific ideology. Its raison d'etre seems mainly to oppose Machel's Marxist government with a vague appeal to capitalism and to a return to more traditional ways, such as polygamy and tribal chieftainship.

The unpopularity of some government measures in rural areas, including grouping people in communal villages and socialization of the distribution system which has caused shortages, has provided some fertile ground for MNR recruitment.

"There is no evidence of people rallying to support the MNR," a western diplomat said. "Nor are many in the rural areas particularly attracted by the government" now that the fervor of independence eight years ago has faded.

Recently, however, Mozambican emotions have reached a danger point in areas hit by sabotage and brutalities. Seven MNR prisoners were shot by firing squads in public executions in January as crowds cheered and carried the presiding officials, including Foreign Minister Joaquim Chissano, on their shoulders. Five handcuffed foreigners were hauled before a crowd of 10,000 in Beira and accused of sabotaging the port's oil storage tanks as spectators shouted, "Kill them!"

This series will examine how the hidden war is bleeding an already destitute country, destabilizing southern Africa and increasing the danger of East-West confrontation in a region rich in minerals and sitting astride strategic sea lanes.

To the nations of southern Africa, the war is part of a massive South African campaign to destabilize its neighbors to prevent successful black rule from providing a positive example to its powerless black majority. They cite the occupation of southern Angola, support for the MNR, attacks on Lesotho and economic pressure on Zimbabwe.

The pressure is most direct in Angola and Lesotho, where South African troops are used and insurgent organizations are believed to receive support from Pretoria. South African policy is more subtle toward Zimbabwe, where destabilization activities could lead to charges from the West that Pretoria is nullifying the vast amount of economic assistance being poured in.

By using the MNR as surrogates, South Africa's policy toward Mozambique seems to fall between these extremes.

South Africa sharply denies all charges of destabilization in the area. In a recent interview with The New York Times, Prime Minister Pieter W. Botha called the accusations "another stunt by Marxist forces," but he added, "If fellow Africans are threatened by the evils of communism, we shall assist them when our assistance is requested."

Defense Minister Magnus Malan came close to acknowledging an active role in a speech to Parliament. The government, he said, would use any methods to fight its enemies in neighboring countries, "even if it would mean we would support anticommunist movements like MNR and UNITA," the Angolan rebels.

The government accuses Mozambique of harboring guerrillas of the African National Congress and allowing them to infiltrate across the border into South Africa. The ANC, which is outlawed in South Africa, seeks to establish black-majority rule, by force if necessary.

Foreign Minister Pik Botha, Malan and top military officials all declined to have interviews with The Washington Post about the MNR.

No western diplomat interviewed in Maputo questioned South Africa's involvement with the Mozambican resistance. "Everybody takes for granted South African support for the MNR," one ambassador said.

The United States, which has the warmest relations with South Africa of the major western countries, has joined in the criticism. The State Department said the MNR "receives the bulk of its support from South Africa."

Chester A. Crocker, assistant secretary of state for African affairs, told South African officials of U.S. concern over destabilization in the area late last year.

Mozambique, a sparsely populated country twice the size of California and bordering on six nations, has scarcely experienced peace since gaining independence in June 1975 after a 10-year guerrilla war waged by the Marxist Front for the Liberation of Mozambique (Frelimo) against Portugal, the colonial power.

Frelimo's victory wrote the deathknell for the white-minority government in neighboring Rhodesia, now Zimbabwe. Mozambique cut off access to its ports and supported guerrillas led by Robert Mugabe, now Zimbabwe's prime minister, in their fight for majority rule.

In response, the Rhodesian government began a surrogate war that continues to this day by establishing the MNR from among blacks and whites who fled Mozambique at independence.

With Mugabe's election in 1980 the operation, including a radio station called Voice of Free Africa, was moved to South Africa.

MNR recruits are reportedly trained at a South African military base in Palaborwa, a copper mining town in the bush about 60 miles west of Kruger National Park, through which they infiltrate Mozambique.

Brig. Jan Klopper, director of operations at the base, told correspondents on a brief tour there in December, "I know of no assistance whatsoever to the Mozambique National Resistance Movement."

However, South African goods have been discovered at MNR bases captured by Mozambican troops and residents of border towns have told of white Afrikaans-speaking troops being involved in attacks, according to the Mozambican news agency.

Two former MNR guerrillas captured by the Mozambican Army, Samuel Agostinho Madanze, 32, and Nassone Francisco Mabunda, 21, gave numerous details of their training "by Boers" at bases in South Africa.

Because of the remote training areas, South Africa has "deniability but no credibility," one analyst said.

The resistance movement is led by Afonso Dhlakama, a black who was expelled from Frelimo in a 1974 anticorruption drive, and Orlando Christina, a Portuguese. Both are believed to live in South Africa, but announcements of kidnapings or battles are usually made in Lisbon by Evo Fernandes, who is in charge of MNR publicity.

Apparently a key aim of South Africa in supporting the MNR is to pressure Mozambique to put a hold on the ANC.

The demand reportedly was spelled out in a meeting in December between South African Foreign Minister Botha and Mozambican Security Minister Maj. Gen. Jacinto Veloso in the South African border town of Komatipoort, the first time a member of the ruling Politburo has openly met with a senior South African official.

"The quid pro quo is there--there's a linkage between South African support for MNR and ANC activities," a western diplomat privy to the talks said.

Mozambique seems to be responding.

Lennox Lagu, the ANC representative here, said, "There are very serious limitations on ANC activities in Mozambique. None of South Africa's neighbors will give the kind of support to ANC that Tanzania gave Frelimo during its war or Mozambique gave ZANU," Mugabe's guerrilla organization.

"There are no radio broadcasts from Mozambique and no cross-border raids like ZANU did," he added. The Mozambican Army, however, has little ability to monitor ANC activities in the mainly desolate border area, lending credence to South African charges of infiltration, particularly through Swaziland, which borders on both countries.

Lagu said ANC attacks on strategic facilities in South Africa are carried out by members living in the country.

"The Mozambican government used to talk more specifically about ANC," Lagu said. "Now they mention the liberation struggles in general instead of ANC."

He said there are far fewer than 100 ANC members permanently living in Mozambique. Most refugees, he said, are moved quickly to ANC offices in Lusaka, Zambia, or Dar es Salaam, Tanzania, a safer distance from South Africa.

Both Lagu and fellow ANC member Indris Naidoo openly admit that the South Africans have infiltrated their organization and know exactly what ANC is doing in Mozambique. Thus, they say, Pretoria knows there are no ANC bases in the country, despite its charges to the contrary.

"The Mozambican government knows," Naidoo said, that "even if it asked ANC to leave, South Africa would continue to support the MNR."

Pretoria, according to that theory, has a longer-run investment in the Mozambican rebels--maintaining the dependence of black southern Africa on it for trade and transport and thus making the price prohibitive for supporting foes of the apartheid government.

The hidden war already has drawn troops from two neighboring countries, Zimbabwe and Tanzania.

About 1,500 Zimbabwean soldiers are based along the vital 188-mile oil pipeline that runs from Beira to Mutare in eastern Zimbabwe.

Diplomats say as many as 200 Tanzanian troops are here to train Mozambican senior enlisted men.

Of more importance to the United States is an estimate by western diplomats that about 800 to 1,000 Soviet, East German and Cuban military and security advisers are in the country. About 15 North Korean soldiers were seen attending a Machel rally in Chibuto in Gaza Province recently.

Nevertheless, Mozambique recently has been seeking to broaden its friendships beyond the Soviet Bloc and there has been a noticeable warming toward Western Europe and the United States.

After an icy beginning when Mozambique expelled alleged CIA agents two years ago, the Reagan administration is moving toward appointing an ambassador to the country for the first time since 1980, an American diplomat said.

The hidden war could put that opening toward the West at peril. If the conflict worsens, Mozambique would undoubtedly have to turn once more to the East for increased military help, polarizing southern Africa along East-West lines.

"If international measures are not taken to stop South Africa from escalating its aggression, Mozambique, in the long run, may require more and more military assistance from the socialist countries," Foreign Minister Chissano said in an American magazine interview.

"We are in a real war, and this war may escalate and intensify in such a way that we may be forced to lean to one side and not be as nonaligned as some countries want to see us," he said. "We know that only the socialist countries are supporting us against South African aggression."

Only the West can apply diplomatic pressure to South Africa.

The East, which has no relations with Pretoria, can provide arms and, in a worst-case scenario, Cuban troops to Mozambique. That could lead to a direct confrontation with South Africa, like in Angola.

For President Machel, who has spent the past two decades first fighting the Portuguese for independence and then defending his soil against Rhodesian and South African forces and their surrogates, that is a route fraught with bloodshed for his destitute nation.

For southern Africa, it could lead to military involvement in the East-West struggle.

For South Africa, however, it would keep hostilities on foreign soil and away from the homeland. Next: the war