In their longest and most extensive incursion into Angola since the 1976 civil war there, South African air and ground forces killed 360 guerrillas of the Southwest Africa People's Organization and captured 150 tons of equipment in nearly three weeks of attacks on SWAPO bases, South African officials said here today.

The officials said the incursion virtually wiped out SWAPO's entire military structure in southern Angola.

[The official Angolan news agency quoted an Angolan Cabinet minister as denying that his country harbored any SWAPO bases. "We only have Namibian refugees who have escaped from oppression, discrimination and racist exploitation," the official said.]

The South African account was its first public official report of its recent activity in southern Angola. The Angolan government called the action an invasion, and it was condemned by the United Nations Security Council last Friday.

SWAPO, a black nationalist movement, is fighting for control of the terrritory of Namibia, which is administered by South Africa under its former name of South West Africa. The 14-year-old bush war has escalated dramatically this year, as a U.N. peace plan is in the final stages of being worked out.

Speaking to reporters at this military base in northern Namibia, Gen. Jannie Geldenhuys, commander of the South African forces in Namibia, confirmed that after a ground and air raid against SWAPO's field headquarters June 10, his forces remained in Angola to carry out what he termed "mopping-up" operations against other bases.

The South Africans said today that 160 guerrillas were killed in the mopping-up operations, in addition to 200 reported killed in the June 10 raid, which was announced by Prime Minister Pieter W. Botha on June 13. Sixteen South Africans died in that operation, and one other had died since then, officials said today.

The three-week operation, during which South Africa appears to have met only minimum resistance from both SWAPO and Angolan government forces, was undertaken to prempt SWAPO plans for an escalation of its insurgency, Geldenhuys said. So far this year, SWAPO has been responsible for the deaths of 78 persons in Namibia, the general said.

"It's my opinion they did suffer a very severe blow; it will take time for them to recognize," he said. "This operation could contribute to a longterm tendency of easing the military conflict.

Geldenhuys refused to say when the South African troops left Angola. Foreign Minister Pik Botha advised the United Nations Monday that all South African forces were out of Angola.

Angolan officials said Tuesday, however, that the South Africans were expanding their presence in Angola. Top party official Lucio Lara told reporters that the South Africans had pushed into Cuando-Cubango Province after taking Huila Province and were in the towns of Katomba, Vindo, Kuamato and Naulilia, according to news agency reports from Luanda, the Angolan capital.

Lara also said that 30 Angolan soldiers and 21 civillians were killed by the South Africans during the previous week, bringing the death toll to 400 since South Africa entered Angola June 7.

The Angolans have said several battalions of South Africans were in their country. Geldenhuys today refused to disclose how many men were involved in the operations.

Geldenhuys also declined to disclose where his men had operated. He said only that the "base areas" attacked were spread out over large areas and separated by "scores" of miles. The South African press agency reported that more than 30 SWAPO underground military storage depots had been destroyed in six separate areas.

Geldenhuys said the Angolan casualties occured during two clashes initiated by Angolan government forces.

He said that South African forces had "literally and figuratively gone out of our way to avoid contact with government forces of the other side [Angola] and with the local population."

Officials said South African airplanes dropped "more than a million" pamphlets in both Portuguese and English warning civilians and Angolan soldiers to steer clear of the fighting between SWAPO and South Africa and saying that the South Africans did not wish to engage the Angolans in the conflict. Reporters were shown samples of the pamphlets.

"We have no record of civilians, women and children, being killed; as a matter of fact I can say with conviction it didn't happen," Geldenhuys said.

SWAPO put up stiff resistance in the June 10 raid, giving South Africa more casualities than in any other single operation of the war. But since then, the guerrillas attempted only twice to fight the South Africans, Geldenhuys said today. Both times the SWAPO forces tried to flee in vehicles, but were stopped by South African aircraft until ground troops reach them, he said.

Reporters today were shown a motley but impressive array of captured equipment reportedly taken from the SWAPO depots. The weapons ranged from World War II Soviet machine guns to the most modern Soviet-designed AK47 automatic rifle. Heatseeking missiles like those that Zimbabwean guerrillas used to shoot down two civilian airplanes were also among the weapons. Soviet trucks and armored personnel carriers with machine guns as well as antiaircraft guns were also on display. The arms exhibition was presented as evidence that SWAPO is better equipped than ever before.