Another six blacks died in racial and political violence today, four of them in the Cape Town area. Meanwhile, an uneasy calm returned to a squatter community near Durban where 53 blacks died in fighting between Zulu and Xhosa tribesmen on Christmas Day.

Precisely what triggered the tribal fighting was still unclear. Reporters who visited the area, called Umbumbulu, today said that groups of armed men were still moving about the packed settlement and that further violence seemed likely.

The deaths reported today, added to those from yesterday's tribal confrontation and other deaths, including six whites killed in a shopping center bombing near Durban on Monday, brought the Christmas week death count to 79.

One of the blacks who died today was killed when police opened fire with shotguns on a crowd of demonstrators in the Cape Province town of Beaufort West, about 300 miles north of Cape Town, where police have clashed several times with black crowds this year and where last October some blacks fired back, wounding two policemen.

A police report on the incident said a riot squad unit used birdshot to disperse the crowd during "sporadic incidents of stone-throwing" in the town's black quarter. A woman also was injured during the shooting, the police report said.

The government has imposed strict limits on journalists' access to townships where violence takes place, and often the only information available on such violence is that provided by police.

Three blacks died today in Paarl, the headquarters of South Africa's wine-making industry near Cape Town and the scene of clashes between police and black groups on Christmas Day when one black man was shot dead.

Police said today's deaths were the result of clashes between rival black political groups, the United Democratic Front and a black consciousness movement called the Azanian People's Organization, but there was no independent confirmation of this.

Police said they prevented further deaths by intervening in the fighting between the two groups.

The charred bodies of two black men were found in Soweto township, outside Johannesburg, and Khayelitsha township, outside Cape Town. They appeared to have been killed by militants who attacked other blacks regarded as collaborators in the apartheid system of segregation.

Reporters who visited Umbumbulu today said troops had been moved into the densely populated squatter area, where bloody battles were fought yesterday between Zulu tribesmen amd members of a subgroup of the Xhosa-speaking people known as the Pondos. They said an uneasy peace had been restored.

They reported, however, that groups of men armed with knives, machetes used for cutting cane in the surrounding sugar plantations and homemade guns with sections of water pipe as barrels, were moving about the squatter camps there and that the atmosphere was tense.

Some said they had been told there could be more violence at the weekend, when workers return from their jobs in Durban to the squatter camps.

Police said they still did not know what triggered yesterday's violence, but Lawrence Schlemmer, head of the department of applied social studies at Natal University, said in a telephone interview tonight that tension had been building up in the area for months because of a massive influx of blacks from the nominally independent Transkei tribal "homeland" to the south.

"This is a result of the failure of the government's homeland policy, which has created a series of explosive squatter camps around South Africa's major industrial cities," said Schlemmer, who is president of the respected Institute of Race Relations.

Umbumbulu is about 30 miles southwest of Durban, and falls in the KwaZulu "homeland" headed by the Zulu leader Gatsha Buthelezi.

Thousands of Xhosa tribesmen have moved there from Transkei during the past decade seeking jobs in the port city as the nominally independent homeland's economy has declined.

Two shantytowns called Umbogendwini and Malakazi, with a combined population of about 150,000, have mushroomed along the transport routes from the Umbumbulu district into Durban.

"The resident Zulus regard the Xhosas who have moved in there as interlopers," Schlemmer explained. "As the pressure has increased on the district's scarce resources of water and land, and as unemployment has risen to about 45 percent, it was more or less inevitable that tribal conflict would erupt."

At this stage the conflict is still largely socioeconomic, Schlemmer said, but it could acquire political overtones and turn into a clash between Buthelezi's Zulu-based Inkatha movement and the more broadly based United Democratic Front, which has been the main activist movement during the past 16 months of black rebellion.

There has been an increase in conflicts between supporters of the United Democratic Front and the politically more moderate but historically warlike Inkatha movement lately, raising fears of a black-on-black civil war in addition to the violence between the security forces and black activists opposing apartheid.

Schlemmer said the growth of huge, explosive squatter camps outside South Africa's industrial cities was a result of the failure of the government's homelands policy, which was designed to create 10 small nation-states for the 31 million blacks in South Africa while reserving 87 percent of the country's land area for the 4.5 million whites, 2.6 million mixed-race "Coloreds" and 850,000 Asians.

A recent study sponsored by the Carnegie Corp. of New York found that the overcrowded, poorly developed and often badly administered homelands have become economic disaster areas. Subsistence agriculture has collapsed as a result of the overcrowding, and the homelands no longer can support their people, thousands of whom are flocking to the industrial cities despite strict "influx control" laws designed to prevent this.

Huge shantytowns are springing up around the cities. The best known is Crossroads, outside Cape Town, which has about 250,000 residents, mostly from the nominally independent Ciskei homeland.

Transkei lies to the north of Ciskei, bordering Natal Province. The flight path of migrants from there leads toward Durban and the shantytowns of Umbumbulu.