South African military forces that invaded southern Angola last week have transformed a large area of the country into a no man's land.

During a tour of part of the war zone with the Angolan military Tuesday not a single civilian was seen for a stretch of 60 miles along the major southern highway leading to the Namibian border. Normally such thoroughfares in Africa are crowded with people.

This town of several thousand population was deserted. Destruction caused by South African air raids, which began Aug. 23, was widespread.

Most of the buildings in the part of the town I saw were leveled or badly damaged, including houses, huts, stores, a makeshift outdoor school, a government building and a pharmacy.

Bits of clothing and household goods were scattered over a wide area where huts made of branches had been badly damaged on the edge of the built-up part of the town. Two broken desks and two blackboards with sums on them were the remnants of the school.

There was no evidence of any military base near the ravaged area, nor was there any concrete indication that the town had been a base for guerrillas fighting for independence for neighboring Namibia (Southwest Africa), as South Africa has claimed. There was no appearance of an attempt to hit a selective target.

The tour, however, left a number of questions unanswered.

Angolan officials could not give any details of casualties, did not produce any bodies or grave sites and would not allow me to interview refugees or visit a hospital in Lubango, the main city in the south 125 miles away, where the injured are being treated. There was also no direct evidence of bloodshed.

The Angolan authorities strictly limited my tour to what they wanted to show me and have me photograph so it is impossible to verify the claims of the local commander. He vehemently denied there were any guerrillas of the Southwest Africa People's Organization (SWAPO) in the area or any surface-to-air missile sites as South Africa has claimed.

The difficulty is that the bush is so vast around Cahama that it is impossible to tell what is beyond immediate eyesight. Also, the key air attack happened nine days before my visit, although there have been other raids since then on the deserted town.

The Angolans displayed only the devastating effects of the aerial attacks, but it seems certain that the ground warfare to the south has caused far more disruption in the lives of the people of Cunene Province.

It was impossible to continue south of Cahama on Tuesday, because the military said fighting was going on only 12 miles away. The South Africans say they have pulled their ground forces back to Ngiva, just 25 miles from the border and more than 125 miles by road from here.

No sound of battle could be heard, but during the visit a South African jet whined overhead, causing a mad scramble of soldiers and civilians away from our Land Rover, across a dry creek bed and into the bush where we hid for an hour before continuing.

The soldiers in my escort knew it was a South African plane without even looking, an indication that the Angolan Air Force is still not operating in much of the southern part of the country, which is about the size of New York State.

While we were hiding in the bush, a huge truck, carrying a tank with troops atop rolled onto the highway. Three others followed after the all-clear.

Either the South African pilot did not see the tanks or he did not care because later the four empty trucks drove back northward.

Diplomats who were taken on a tour of the area Sunday saw three other tanks being taken toward the war front. Those movements, plus the arrival of military reinforcements in Lubango, are indications that the fighting is continuing despite South African claims that its forces are withdrawing.

Angolan troops have pulled out of Cahama. My visit was protected by troops based in Tchibemba, about 50 miles to the north. Other than our group, the only sign of life in the town during the tense 90-minute stay was a herd of goats. A diplomat on the Sunday tour, which covered more of Cahama than I saw, counted 81 destroyed buildings.

Officials say most of the inhabitants are either living in the bush or have fled to Lubango. The government has told the United Nations, which is investigating a disaster relief program, that 130,000 persons have been displaced by the South African offensive.

Diplomats voiced some doubt about the number, however, since very little is known about the current population of the area after years of intermittent warfare except that it is sparse.

The Angolans did allow me to see one destroyed facility of military significance: a radar installation outside the town of Tchibemba, almost 50 miles north of Cahama.

One of the radars was destroyed and two others were knocked out of operation. An official said it was "not within my competence" to say where the radar equipment came from or when it had been installed, but Soviet markings were visible and the concrete work around the area had the appearance of being new. A quote by Cuban President Fidel Castro is posted near the destroyed radar site.

The local commander, who declined to be identified, said five South African jets swooped in low early in the morning of Aug. 24, to take out the radar. He gave no details of fighting but vehemently denied any SWAPO presence.

"There is no SWAPO in Tchibemba, not in Cahama, and not in Xangongo," which is farther south and was taken by the South Africans, he said.

He said the South Africans attacked with French Mirage and British Canberra and Buccaneer jets and angrily added: "South Africa is receiving weapons from Western countries. The Reagan administration is helping them and also the puppets," a reference to antigovernment guerrillas known as the Union for the Total Independence of Angola (UNITA), which receives South African support.

Less than a mile away from the radar installations the officer, his face contorted with emotion, showed me the burned-out remains of a small settlement. The only remaining signs that there had been life there were the rotting corpses of two steers shot up by the pilots and two small facilities for storing corn.

The ground was littered with straw, some of it charred, the only remnants of the villagers' huts other than the small stakes used to lay out the settlement.

At other stops, the troops could not provide any information on the number of casualties or the population of the sites.

South Africa has said its forces killed approximately 450 Angolan soldiers and SWAPO guerrillas.

There were unconfirmed reports that South African troops burned the bodies of African soldiers killed in the fighting farther south. If true, the action would further alienate the people, since African tradition generally bans cremation.

The Angolan military camp at Tchibemba that makes up most of the town was not attacked.

Like other towns between here and Lubango, the major city in southern Angola about 120 miles to the north, the base shows the colorful remnants of Portuguese rule. Tchibemba is probably one of the few military facilities in the world where the basic color of the buildings is pink, highlighted by trims in other pastel shades.

There are also reminders of the current Marxist government at the base and throughout the drive southward. Paintings or billboards feature Marx, Lenin, Engels, Castro and Angolan President Eduardo dos Santos. Most commonly seen are pictures of the revered late president Agostinho Neto, while reproductions of Soviet President Leonid Brezhnev are fairly rare.

At the entrance to the base there is a thumbs-up Lenin exhorting, "Study, learn, assimilate." Next to him is Neto saying, "Commanders, give orders!"

The impact of the air raid on the population has been felt far beyond the target sites.

Except for a few militiamen, the town of Chiange, about 20 miles west of Tchibemba, was deserted and all power had been turned off. The South African jets flew low over Chiange on the way to the raid to Tchibemba.

The people are sleeping in the bush nearby, still frightened to stay in their homes eight days after the fly-over, said one militiaman.

A sliver of a moon and a star-lit sky gave Chiange an eerie quality as we drove without headlights through the one street in the town.

The next day we had to drive 15 miles north of Tchibemba before we saw the first people.

Soon, however, we were back in traditional Africa. A bare-breasted woman, adorned with heavy beads, walked along the road. She could have been photographed for a postcard.

A short distance to the south the picture is a bit different.