'Nonsense,' Botha says; S. Africa denies rebel links

South Africa continues to dismiss, rather than answer, the growing chorus of allegations that it is destabilizing its neighbors. The charge is not a new one. But it is reaching a high pitch as the 1983 political season opens here.

Concern over Pretoria's intentions is running high because most analysts see mounting economic and political instability in most of the nations of southern Africa. These analysts worry that an already bad situation could quickly grow worse with nudges from South Africa. South Africa's opposition Progressive Federal Party honed in on the destabilization theme in parliamentary debate this week - warning the government must not be seen to be involved in such actions.

In response, Prime Minister Pieter W. Botha did not reply to allegations that South Africa supports rebels in Angola, Mozambique, and other neighboring states.

The prime minister made a blanket dismissal of charges of destabilization, calling them ''complete nonsense.'' He went on to claim that South Africa was, in fact, seeking greater dialogue with its neighbors, pointing to high-level talks that have been held with Angola, Mozambique, Lesotho, Swaziland, and last year's much publicized summit with Zambian President Kenneth Kaunda.

Botha's response almost surely will not lay suspicions to rest. Indeed, those convinced South Africa is bent on undermining neighboring black governments - or at least keeping them off balance - see a policy that deliberately combines the use of carrot and stick. Military actions, it is argued, are designed to force hostile governments into dialogue and a more benign stance vis-a-vis South Africa.

Destabilization allegations are difficult to substantiate. Some of the rebel groups have indigenous roots making it hard to assess to what extent they might owe their existence to South African support.

However, the circumstantial evidence against Pretoria is strong, particularly in the cases of southern Africa's most troubled states - Angola and Mozambique.

* The Mozambique National Resistance (MNR) is fighting an increasingly bold battle to oust Mozambique President Samora Machel. The rebel movement was allegedly organized by the former Rhodesian security forces in 1976 to counter Mozambique support of black nationalists fighting against the former Rhodesian government.

After Rhodesia became Zimbabwe, South Africa allegedly supported the MNR. The Mozambique government has documents that it claims were captured from the MNR showing a South African link.

South Africa denies any link, but the evidence is apparently so strong as to prompt the US State Department to say in a recent article in Africa Report that the MNR receives ''the bulk of its support from South Africa.'' It marks a rare public rebuke of Pretoria by the Reagan administration.

* The UNITA (National Union for the Total Independence of Angola) rebel movement in Angola is widely believed to have South African support. UNITA has openly acknowledged it has ''contact'' with South African forces in southern Angola.

South Africa makes regular forays into Angola, saying it is pursuing SWAPO (South West Africa People's Organization) guerrilla forces that are fighting South Africa for control of Namibia. Many analysts see another reason for the incursions: to keep Angola on the defensive and punish it for providing SWAPO with sanctuary and bases.

Other, more isolated instances have suggested South African involvement in destabilization efforts. A 1981 coup bid in the Seychelles turned out to have had support from some members of the South African Defense Force and intelligence service. And last year three white South African soldiers were shot on Zimbabwean soil. In both cases, South Africa claimed individuals were acting without official consent.

More recently South African forces swept into Lesotho, claiming they were striking at alleged ''terrorist'' members of the underground African National Congress (ANC), South Africa's best-known black political organization. Some observers say the December raid, which resulted in 37 deaths, may also have been a veiled attempt to ruffle Mozambique. Several days before the Lesotho attack, South Africa had warned Mozambique not to allow ANC activity there, adding it would not want to see Cuban troops in Mozambique.

Zimbabwe recently charged that South Africa is aiding dissidents in that country and is responsible for attacks on Zimbabwe's oil pipeline from Mozambique.

While Pretoria denies destabilization efforts, it has established its intention of invading neighbors that support groups like the ANC. Many analysts say destabilization efforts may be the covert side of that policy.