South Africa admitted tonight that it is currently engaged in a military operation in southern Angola, but denied that the operation is directed against the Angolan government or is on the scale claimed by the Angolian authorities.

In a letter to United Nations Secretary General Kurt Waldheim, South African Foreign Minister Roelof (Pik) Botha said that "a small combat team" has entered Angola to take action against the guerrilla movement of the South-West African Peoples' Organization (SWAPO).

While the South African statement confirms reports that South African forces are inside Angola, it does not resolve conflicting claims about the extent of their activity there.

The Angolans have said that a 2,000-man force invaded southern Angola June 7 and occupied the towns of Evale, Mongua and Cuamato. Botha said tonight that "allegations that South African employed force-levels of several brigades are ludicrous."

In his letter to Waldheim, Botha did not specify the size of the combat team but said it was in the process of returning to bases in the territory of Namibia (South-West Africa). The team's withdrawal will be complete "within the next day or so," according to Botha's letter.

The foreign minister denied that the South African forces were directing their activity against Angolan government troops. However, Botha disclosed that the Angolans shot down a South African helicopter and then attacked the crew members after it had crash-landed. The pilot killed several Angolan soldiers during his successful escape, Botha said.

In New York, Angola's chief delegate to the United Nations said his country would call for outside military help if its forces were unable to repulse an invasion by South African troops, Reuter reported.

[U.N. delegate Elisio de Figueirado said that fierce fighting was going on in two provinces inside the country since Monday and claimed that an estimated 6,000 invaders had inflicted heavy casualties.]

[The U.N. Security Council later condemned South Africa's invasion of Angola and asked Pretoria to withdraw all its troops immediately. The vote was 12 to 0, with three nations abstaining, among them the United States.]

Botha also said South Africa had "no aggressive intentions against Angola and its people" and that allegations of civilian casualties and destruction of property were unfounded. "Such casualties as resulted involved only SWAPO personnel or persons involved with SWAPO activities," he said.

South Africa "had no choice but to eradicate threats from countries which openly harbor terrorists," he added. Angola allows SWAPO to operate from its territory to carry out a guerrilla war against South African forces controlling Namibia.

Botha said, "It is SWAPO who should be condemned" at the United Nations "because of its activities which involved the deaths of 46 civilians in Namibia between March and May of this year."

Continuing South African pressure on SWAPO positions in Angola is seen by observers here as an attempt to weaken the guerrilla movement militarily before U.N.-sponsored elections take place in Namibia. Two weeks ago, South Africa carried out a major raid against SWAPO that military officials here described as a "tremendous success."