South African air and ground forces raided Namibian guerrilla bases in southern Angola this week, leaving 200 guerrillas and 16 troops dead, Prime Minister Pieter W. Botha announced today.

The raids and a number of other recent clashes indicate that the 14-year-old bush war with guerrillas of the South-West Africa People's Organization (SWAPO) is escalating dramatically.

South Africa administers South-West Africa in definace of the United Nations, which has supported SWAPO's demands for independence for Namibia -- the territory's other name.

The casualties admitted by South Africa, including at least three black Namibians, are the largest in any single reported operation. They bring the South African death toll to at least 59 this year, almost double that for all of 1979. Guerrilla deaths are put at 632.

Speaking in Parliament, Botha said the initial attack on camps in Angola, to the north of Namibia, were spread over 25 square mils and included SWAPO's field headquarters.

Botha, who is also defense minister, said that assault lasted six hours and "was continuing the following morning." He did not specify which day the attack began.

"More than 200 terrorists were shot dead and a large amount of equipment, estimated at more than 100 tons, fell into the hands of South African forces," he said.

"The process of collecting the equipment . . . has almost been completed," Botha said, indicating that his troops were still in Angola this afternoon.

The raids came as negotiations over a U.N. plan for a cease-fire and elections in Nambia reached their final stage, according to Western diplomats. Although only last-minute details are said to hold up implementation of the plan, the South Africans are said to have cooled to the proposals.

Marxist guerrilla leader Robert Mugabe's electoral victory in neighboring Zimbabwe has made South Africans even less enthusiastic about elections in Namibia than in the past. Mozambique, on South Africa's northeast border, also is under Marxist rule, as is Angola.

Botha said he "noted with appreciation that Angolan armed forces have until now withheld themselves from giving assistance to SWAPO during the present operation.

"Seeing as it is my govvernment's stated policy that we want to live in peace and harmony with our neighbors, I wish to express the hope that the Angolan government forces will continue exercising this attitude," Botha said. He warned, however, that by sharing some bases with SWAPO guerrillas they "thereby expose themselves."

The South Africans did not give details on how the South African casualties occurred but the ranks of the 16 men suggest they were a unit and were perhaps shot down while being ferried in a helicopter.

For the first time, the government controlled television station was allowed to film a cross-border raid for broadcast. This evening's news showed the operation involved helicopters, tanks and armored personnel carriers.

Angola reported yesterday that Angolan anti-aircraft batteries shot down three South African Mirage fighter-bombers last Saturday during a raid on Namibian refugees in a camp in southern Angola. A South African military spokesman described the radio report as "propaganda."

"I wish to again warn SWAPO leaders that wherever they should establish bases, we will track them down and destroy them," Botha said, thanking the attacking force for its demonstration of "power and capability to combat anarchy, terrorism and communism."

A South African assault two years ago, similar to that announced today, left more than 800 black nationalist forces dead and delayed U.N. negotiations for a couple of months.

Although South Africa apparently hopes to see an internationally acceptable settlement in Namibia, it is doubtful of the United Nation's impartiality because of the General Assembly's longstanding recognition of SWAPO as the "sole legitimate representative of the Namibian people."

The South Africans also have little confidence in a 7,500-man U.N. peacekeeping force that would supervise the cease-fire.

Most political analysts believe that South Africa is seeking to gain more time before an election, despite the rising cost in lives, to build up the image and accomplishments of the moderate parties it is supporting in Namibia.

To this end, South Africa has taken a number of steps in recent weeks to give these internal forces more powers and to show the black population in the semi-desert territory that changes are being made.

Those steps include the establishment of a ministerial council to assist the South African administrator in the territory and to take control of a 2,000-man contingent of Namibianborn soldiers now in the South African Defense Force. In addition, a tough law was passed prohibiting racial discrimination in public places, with stiff penalties for violaters.