JOHANNESBURG, NOV. 11 -- The South African military command said today that its forces fought against Soviet and Cuban troops in southern Angola last month to drive back a major attack by Angolan government troops.

It was the first time that South Africa has acknowledged that its forces fought alongside anticommunist guerrillas in what has been described as the biggest battle of the 12-year-old Angolan civil war.

South African Defense Force Chief Jannie Geldenhuys said in a statement issued in Pretoria that South African troops were "compelled to take limited action against surrogate forces" in last month's battle between guerrillas of Jonas Savimbi's Union for the Total Independence of Angola (UNITA) and Angolan government forces.

Savimbi in an interview last month emphatically denied that South African forces had come to his aid. Since then, he has boasted repeatedly that his guerrillas drove back thousands of Angolan, Cuban and Soviet troops without any outside help.

Geldenhuys gave no details of the South African intervention and made no mention of casualties.

U.S. officials said earlier this month that they had no evidence of Cuban combat troops participating directly in the fighting during the Angolan offensive.

However, they said that for the first time Soviet officers acting as advisers had operated at the front line of fighting as well as Cuban advisers "down to the company level." One official said, "They {Soviet and Cuban advisers} were more aggressively involved on the ground than in past offensives."

There was also "some Cuban air support," the official added. U.S. officials also said it was "certain" that the Cubans and Soviets had been involved in planning the offensive and that there was evidence of Cuban pilots.

It was understood that the South African intervention came after UNITA guerrillas had pushed the Angolan Army across the Lomba River in a decisive battle on Oct. 13 and after Cuban mechanized infantry units and tank corps, directed by Soviet advisers, joined the fighting.

Geldenhuys said that the Russians and Cubans, using tanks, sophisticated ground-to-air missiles and fighter aircraft, including MiG23 and attack helicopters, entered the battle after the Angolans had been beaten decisively.

As a result of the setbacks, he said, government troops withdrew from the Lomba River and suspended their dry season offensive against Mavinga, a strategic gateway to UNITA headquarters in the southeastern Angolan town of Jamba and a center of agricultural production for all of the territory controlled by Savimbi's U.S.-supported guerrillas.

During a briefing in Washington on Oct. 30, U.S. officials said there was "little doubt" that South African artillery, as well as "some" South African aircraft, played a role in UNITA's victory. But they gave no indication of major South African intervention in the battles.

On Oct. 4, South African Defense Minister Magnus Malan said that South Africa maintained only a periodic "limited presence" in southern Angola which was confined to fighting South West Africa People's Organization (SWAPO) guerrillas attempting to infiltrate into Namibia, bordering Angola in the south.

Angolan government officials in Luanda said at the time that South Africa intervened massively with ground and air support and that more than 10 South African planes had been shot down and nearly 100 South African soldiers killed.

During the Angolan Army's 1985 dry-season offensive against Mavinga, officials in Luanda said the South Africans intervened massively with ground and air support, although Savimbi and officials in Pretoria have denied it.

In his statement today, Geldenhuys said, "This intervention is further evidence of periodic active Cuban destabilization in Angola, which started in mid-1975." He was referring to the start of the civil war and the arrival of Cuban troops in November 1975, after UNITA guerrillas and South African troops began capturing territory along Angola's west coast and closed in on the capital of Luanda.

South African troops withdrew from Angola in January 1976, after UNITA seized control of the southeastern quarter of the country.

In his statement, Geldenhuys said, "The {South African} security forces intervention is not only in support of UNITA, but as the minister of defense has repeatedly said, it is in South Africa's interest to safeguard Namibia from SWAPO terrorist activity."

Geldenhuys said the Army's motive for intervening was also based on a realization that continued Angolan government control of parts of southern Angola "would give the African National Congress greater facility of movement."

As it is, the Angolan government provides the ANC with base and training facilities.

Washington Post staff writer David B. Ottaway contributed to this report.