Zambia's national airline plans to start direct flights later this year to South Africa -- the first time an independent African nation unfriendly to Pretoria will have initiated such links with the white-controlled government.

The move is a major outgrowth of the Rhodesia peace settlement and means that Zambia, one of the leaders in the annual African effort to impose United Nations economic sanctions against South Africa, will be expanding commerce and possibly tourism with black Africa's most reviled foe.

For South Africa, opening such links would be a significant step toward building its "constellation of states," an effort to surround itself with friendly neighbors in southern Africa through shared economic interests.

The projected air link, which is expected to begin via Salisbury by August, is an example of how Rhodesia's long-hositle neighbors are rushing to reap the benefits of a peaceful settlement.

Ironically, at the same time they are sharply criticizing Britain's temporary colonial administration in Rhodesia and are threatening to ignore the results of next month's black-majority-rule elections. Such a move could lead to a resumption of hostilities and the collapse of the economic benefits being widely hailed as the fruit of peace in Rhodesia.

As has often been the case since Rhodesia's whites declared illegal independence in 1965, what the key actors do is more significant than what they say.

Zambia Airways managing director, Brig. Gen. Enos Haimbe, disclosing plans for the Lusaka-Johannesburg route in an interview last week, acknowledged that it is only feasible to operate the flight over Rhodesian airspace, an impossibility if the war resumes.

He said talks are under way with South Africa to assure Zambia that its black passengers will not suffer discrimination in transit in the apartheid nation, the only obstacle to starting flights.

Last week in a forerunner of the service, a Zambia Airways jet flew 14 surprised passengers nonstop from Johanesburg to Lusaka after flying south on a charter. Just three months ago President Kenneth Kaunda was accusing 600 South African troops of "invading" the southwestern part of the country, the site of bases for guerrillas fighting to free Namibia from South African control.

Asked if the government-owned airline was putting commercial concerns ahead of national interests, Haimbe said that if sanctions were ever voted the airline would abandon the route. But he indicated that he did not expect sanctions any time soon, saying: "We all know we are going to die, but why stop eating before you die."

A senior aide to Kaunda made it clear that Zambia was determined to put the war behind it and get on with economic development.

"Once Rhodesia and Manibia are free Zambia will no longer be a front-line country. Over the last 15 years we have sacrificed virtually everything to gain their independence. Now, we will buy from the south whatever we can," he said, adding that South Africa was Zambia's cheapest source of imports.

The official virtually acknowledged that the issue of sanctions against the South Africans, long blocked by the West, was dead. He said, tongue in cheek, that Zambia "will denounce them [the South Africans] morally" but go ahead and trade and at the same time expect the West to apply sanctions.

Zambia never had a ban on trade with South Africa, the official emphasized, and pointed out that such commerce had steadily increased through the early 1970s until the war led to the closing of the Zambian-Rhodesian border. Two-way trade, mainly Zambian imports, averaged about $90 million annually in 1970-72 but had dropped by about half by 1977-78.

So far South Africa has not asked for reciprocal rights but Haimbe expects they will eventually be granted, a move that could lead to the end of the virtual ban on South African Airways flights over black Africa. To fly to Europe the airline has to use a circuitous route, usually refuelling at the Atlantic islands of Las Palmas or Iiha do Sal.

The only black African countries with air links to South Africa are Malawi, the sole African nation to recognize Pretoria, and Mozambique, which is heavily dependent on South Africa economically.

Both Zambia and Mozambique have been quick to reopen commercial links with Rhodesia, sending a clear message to the Patriotic Front guerrillas they supported in the seven-year war that the two front-line states prefer a peaceful settlement of the Rhodesian issue.

Zambia Airways was the first airline to expand service to the new temporary British colony, even ahead of British Airways. Two of the three road crossings have already been opened with the third, the spectacular Victoria Falls frontier point, due to open Friday.

Surrounded by eight nations, five of which have experienced wars or revolutions in the last decade, landlocked Zambia saw its access to the sea cut off by the Rhodesian war.