South Africa today gave the first official account of its six-month involvement in the Angolan civil war, saying that the South African-supported side could have easily conquered "the whole of Angola" and claiming that at the height it committed just under 2,000 troops and advisers.

In a statement released to local military correspondents, the South African Defense Force claimed that the only factor barring South Africa and its allies from a total victory was a decision by Jonas Savimbi, leader of the National Union for the Total Independence of Angola (UNITA), to limit an offensive in October 1975 to retake the southern half of the country.

The overall impression given by the official South African account is that Cuban military intervention complicated matters but would not have prevented a military victory by Sough Affrica and its allies had it not been for Savimbi's refusal to sanction the taking of Luanda and rejection of South African advice by Holden Roberto, leader of the other Western-backed faction. In other words, South Africa places the blame on its own Angolan allies.

[The new account differs with some of South Africa's own earlier accounts. In an intreview with the Washington Post's Bernard Nossiter, South African Defense Minister Pieter Botha said in February 1976 that his country was then holding a 50-mile-deep buffer zone with 4,000 to 5,000 troops - more than double the total number the South Africans now say were involved at the height of their intervention.]

Savimbi, today's statement said, insisted that he was only interested in controlling his traditional area because he was determined to reach a settlement with the MPLA to the advantage of the whole of Angola." The popular movement for the Liberation of Angola (MPLA), backed by the Soviet Union and Cuba, won the way and now rules Angola.

The ministry said that on the eve of the war torn Portuguese colony's independence Nov. 11, 1975, South Africa and its allies held a 500-mile-long offensive line stretching from north of the port of Lobito eastward to Santa Comba and Luso and that they were able to move northward "with the greatest of ease," taking all the territory up to the Cuanza River.

At one point, South African-led forces were within 55 to 60 miles of Luanda the capital, and the city might have been taken, a senior officer told South African military correspondents. "Our instructions, however, were not to take Luanda but to safeguard Dr. Savimbi's traditional area."

The South African decision to withdraw came on Jan. 10 after the Organization of African Unity summit meeting in Addis Ababa failed to reach a decision on the civil war. The South African pullback was a "purely political one," the officer said.

South Africa, he said, was not prepared to fight alone for the West, and the withdrawal was completed by Jan. 22, except for some troops left near the border with South African-administered Namibia. They were withdrawn March 25.

There was no indication from the account of the one press conference, later published by the South African Press Association, that the unnamed senior military officer briefing local journalists had blamed by name or inference the United States for failing to back the South African venture. Many South African officials have expressed in private their deep disappointment at the American attitude and even hinted that it was crucial in south Africa's decision to withdraw.

The only bitterness manifested in the South African military account was toward Roberto, leader of the U.S.-backed National Front for the Liberation of Angola, whose forces were concentrated in Northern Angola.

It said that Roberto had "thrown to the winds" South African military advice not to launch an offensive to try to take Lauanda and to concentrate instead on consolidating his position in the north. The National Front attack Nov. 6 on impla-Cuban defensive positions just outside the capital was "a total disaster," the statemen said.

"Against the advice of South Africa, Roberto gambled away his forces on careless attacks, instead of using them for the retention of his traditional areas of influence," it said.

The account gave for the first time the South African version of the highlights of the civil war, but there was no indication of total casualty figures for any of the fighting forces.

It did say, however, that one unnamed Cuban general died and that in a battle for what was known as "Bridge 14" near Catofe in central Angola, lasting from Dec. 9-12, some 200 Cubans and 200 MPLA troops were killed and that there were four South African losses.

The decision by South Africa to disclose its version of the war comes after a long semi-official report of the Cuban involvement by the Colombian Communist writer Gabriel Garcia Marquez published last month by The Washington Post. Both Marquez and South Africa seem to agree that the battle for Bridge 14 was a Cuban disaster - but the Colombian claimed that South African forces got no closer than 120 miles to Luanda.

The South African account of the war said Pretoria's initial involvement in southern Angola resulted from the "chaos and confusion" reigning there that had made it possible for guerrillas belonging to the Southwest African People's Organization (SWAPO) to step up their raids into South African-administered Namibia.

The second motive was the threat to the South African and Portuguese hydroelectric power projects at Ruacana and Calueque on the Angolan-Namibian border, according to the statement.

The statement said that both UNITA and FNLA appealed to South Africa for support against "Communist infiltration in Angola" and that South African forces in a hot pursuit operation against SWAPO guerrillas came across Cuban war suppliles, "which placed the cecurity situation of southern Angola and the (Ruacana and Calueque) water schemes in a completely different light."

T"Dr. Savimbi had full confidence that if he could maintain his authority in his traditional area (the south), the MPLA would have agreed to a peaceful change of government in which all three movements would have been represented" the statement said."This is what he favored all along rather than to involve his country in a bloody struggle which could not only have cost innocent lives of his people but also caused the destruction of his country's infrastructure.

"For this reason, it was decided to give help and support on only a limited scale," it said.

The first South African army officer was sent to Silva Porto, a UNITA stronghold, on Sept. 24, 1975, to help plan an operation to stop a popular-movement toward Nova Lisboa, the statement said. His task was to advise UNITA and help it to hold Nova Lisboa "at all costs."

He pas joined by 18 instructors armed with three antitank weapons and a few machine guns. With a company of UNITA soldiers, they halted an MPLA column halfway between Nova Lisboa and Lobito on Oct. 6. This was apparently the turning point in the war, after which South African-supported UNITA and FNLA forces went on the offensive.

Leading this offensive, according to the South African account, was the "Zulu Battle Group," consisting of about 500 UNITA and FNLA troops commanded by six South African officers and seven noncommissioned officers. The group reportedly covered 1,975 miles in only a few days, engaged in 21 clashes or ambushes, 16 quick attacks and 14 major attacks. Between Oct. 19 and 28, it took back five major cities in the south. MPLA loses during this time were 210 killed, 96 wounded and 56 captured.

Tne ZuZlu Battle Group suffered only light casualties, including a South African soldier and four FNLA soldiers killed and 41 others wounded the account said.

Another key unit was called the Foxbat Battle Group was responsible for the Cuban defeat at Bridge 14. It consisted of three FNLA-UNITA companies, a company of South African infantry and an armored car squadrom supported by eight South African 140mm and 80mm guns, a platoon of mortars and an engineering unit.

In the four-day battle, the South Africans captured numerous Soviet made 122mm "Stalin organ" rocket launchers in addition to killing 200 Cubans. Only four of their own soldiers were lost, the statement said.

Total South African losses during the war are reported here to have been 33 killed. Estimates of the number of Cubans that died range up to 2,000.

The account tells how the Zulu Battle Group swept up the coast seizing Benguela, Lobito and finally Novo Refondo on Nov. 13, 1975, two days after Angola's official independence, while the Foxbat Group came up the inland road to Quibale.

But the arrival of Cuban reinforcements and "unlimited number of Russian armaments" after independence changed the military situation drastically, forcing South Africa to increase its initial forces of some 300 instructors and soldiers to "just under 2,000 men (logistical elements included)" the statement said.

The heaviest fighting between South African-led units and Cuban forces appears to have taken place around Quibale in mid-December, when the Cubans for the first time used jet aircraft and tanks, according to the statement.

It goes on to list the victories scored by South African-led forces in the east, particularly in Luso, where 250 MPLA soldiers were killed and large amounts of Soviet arms seized after its fall on Dec. 11.