Prime Minister Pieter Botha admitted today that South African troops clashed with Angolan forces in Angola, but he played down the South African presence in that country, saying claims of an invasion were "an absolute misrepresentation" of the facts. Botha also for the first time publicly called on Angola to meet his government for discussions.

Speaking in Parliament in Cape Town, Botha said South African forces werej on a follow-up operation against guerrillas of the South-West Africa People's Organization, which is fighting for control of the territory of Namibia, also known as South-West Africa.

The prime minister defended his country's right to pursue the guerrillas across the Namibia border to their sanctuaries in Angola. "The so-called invasion to which the Angolan authorities refer was simply one of these follow-up operations, and it would have been carried out without incident if the Mpla [Angola's ruling party], as in the recent past, had not intervened," Botha said.

"[South African] security forces were, however, prepared for such intervention and defended themselves to good effect and at the same time succeeded in destroyng several terrorist systems and arms depots," Botha added.

"I trust the MPLA government will now take note of our request not to intervene and our ideal to live in peace with our neighbors; that they will stop getting involved in operations which are not aimed at them, but against terrorism, and to respond to our request to enter into a dialogue situation with us."

Botha did not elaborate on what he meant, but an official of the Foreign Ministry said later it should be seen as a mark of "our society to enter into dialogue with them and to iron out the differences between us." He said such a meeting did not have to be public.

South African and Angolan officials have met secretly on several occasions in the past to discuss a reduction in the hostility between them, but each time, for different reasons, the talks have had no tangible result.

Notwithstanding Botha's attempts to minimize the presence of his forces in Angola, there are indications that it is a significantly major operation that is part of a more aggressive pattern of cross-border activity by the South Africans over the past two months.

At the end of July, Maj. Gen. Charles Lloyd, commander of South African forces in Namibia, told foreign and local journalists that as a result of new "hot pursuit" tactics adopted by the South Africans, 225 SWAPO insurgents had been killed that month in "Operation Carnation." This was a steep increase over previous monthly tolls.

Two weeks ago Lloyd warned that South Africa would not hesitate to fight Angolan or Cuban troops who came to the assistance of SWAPO and added that South Africa was preparing for an escalation in the war.

News services reported the following developments:

Despite South Africa's claim that the extent of its military push against guerrillas in Angola has been overstated, Western leaders demanded the forces be withdrawn and sent strong protests to the Pretoria government.

West German Foreign Minister Hans-Dietrich Genscher said he found the South African action "unacceptable" and called in the South African ambassador in Bonn today to protest it.

In London, the British Foreign Office said it summoned South Africa's ambassador, Marais Steyn, to the office today and said the troops must be removed.

The South African ambassador to France was told by the French Foreign Ministry that France regards the attack as an attack on Angola's sovereignty.

Canada's External Affairs Department said the attack "strikes a serious blow in southern Africa and serves only to heighten tension in the area. "

The four nations have worked with the United States in attempting to get South Africa to give up control over South-West Africa.

The Soviet Union also demanded with withdrawal of South African troops from Angola today and declared support for the Luanda government.

U.N. Secretary General Kurt Waldheim broke off hsi vacation in Austria and planned to return to New York to deal with the "grave developments" in Angola, a spokesman said.