Nobel Peace Prize laureate Desmond Tutu and a fellow Anglican bishop waded into a mob outside the cemetery here today to rescue from almost certain death an alleged policeman-informer who was being pummeled and dragged toward his burning car.

As the bishops left the cemetery where four blacks had been buried in an emotional funeral, they saw the crowd attacking a black man with whips and fists. The two churchmen, clad in their purple vestments, pushed their way to the man and pulled him back from the mob. They took the man, bleeding from his face and throat, to a nearby car, and Bishop Simeon Nkoane escorted him from the area.

People in the crowd said persons from a neighboring township had identified the man as a policeman. He was prevented from leaving the area and dragged from his car, which was overturned and set on fire.

"They were going to put him on top of his car," said a participant in the fracas. "That was to be his funeral pyre."

The drama unfolded as black residents buried four of their dead from previous antigovernment violence, then resumed skirmishing with riot police in the battle they are waging for control of the streets and alleys of this dusty township east of Johannesburg.

After the funeral ceremony, hundreds of youths took to the streets, taunting police in armored personnel carriers that roamed the periphery of the town. After several feints, the vehicles entered the area, with police firing tear-gas cannisters and rubber bullets into groups of rock-throwing youths.

There were no reported deaths today to add to the toll of at least 13 blacks who have died in the unrest that began last Friday in the collection of ghettos, scattered among broad empty plains and mine slag heaps, of the area known as the East Rand. Police said today two more bodies were found in Kwa Thema, where at least seven others had died yesterday as mourners were conducting another funeral. Police acknowledged killing the seven blacks yesterday, saying they were attacking the homes of black policemen. But there was no statement today about how the other two died.

The recent shootings were among the bloodiest outbreaks of violence here in 10 months of resistance against South Africa's system of racial segregation. More than 400 blacks have been killed.

The commissioner of police, Gen. P.J. Coetzee, today denied accusations that his men had indiscriminately killed Kwa Thema residents during yesterday's unrest. Witnesses have charged that the police shot tear gas and rubber bullets into a local movie house and then fired upon people as they emerged, killing seven.

"In every case where a person died, the police acted in self-defense or in the defense of the property of a policeman," he said in a statement.

Duduza is a bedroom community of at least 50,000 people who work in nearby mining and industrial towns. In recent days, residents have rendered the township virtually off-limits to police and local officials. Residents say all of Duduza's black police and local councilmen, who are treated by the mob as sellouts in the pay of South Africa's white-minority government, have been forced to abandon their homes here. Burned-out, windowless shells are in many cases all that remain.

The crowd started gathering early this morning. Mourners brought to a local playing field the coffins of four men, ages 19 through 21, killed here two weeks ago when the Soviet-made hand grenades they were carrying exploded in their hands. Police have offered no official explanation for their deaths but have suggested the men were on a mission to murder local officials that was organized by the outlawed African National Congress, South's Africa's leading resistance movement.

Many here say they believe the men obtained the explosives from a police agent who had doctored the grenade pins.

Either way, the crowd today embraced the four as martyrs. Their coffins were propped on chairs in the middle of the field and decorated with plastic flowers that blew off in the wind during the funeral service.

Enoch Makhalemele, a Duduza community leader, told the crowd of about 5,000 people they were burying "our sons, the future leaders of South Africa. For how long, dear God, is this going to carry on? Are we going to do it every day?"

While they gathered, nine police armored personnel carriers could be seen watching from a nearby ridge and a police spotter plane circled overhead.

Most of the crowd were young people, many wearing freshly printed yellow T-shirts with the names and faces of the dead on the front. They sang banned freedom songs and unfurled a large banner with the African National Congress' colors of yellow, black and green. Many came from groups affiliated with the United Democratic Front, a broad coalition of community political groups that the government contends is the domestic stalking horse for the exiled congress.

Tutu, the 1984 Nobel prize winner, said he had broken off attending a provincial Anglican synod to come here "to express sympathy, support and concern" with the mourners. He denounced South Africa's system of legal segregation known as apartheid as "totally immoral" and told the crowd, "We have no doubt at all that we are going to be free."

The bishop, who advocates nonviolence in opposing white rule, referred only obliquely to the circumstances of the deaths of the four young men, saying, "Let us use methods in the struggle which we are not ashamed of."

Tutu was accompanied by several Anglican clergymen, including Bishop Nkoane, who lives in Kwa Thema and who said he had spent yesterday attempting to defuse the violence in his township. Nkoane said his house had been firebombed twice last month, adding, "I find it very difficult not to believe that it's the police" who were behind the incidents.

Later today, five other black policemen had a narrow escape when they were caught by the crowd in a trash-strewn field near the cemetery. They fired tear-gas canisters into the crowd and ran to a police pickup truck that drove into the area to rescue them. After that, riot policemen in armored vehicles poured into the township firing tear gas and rubber bullets.