Nobel Peace laureate Desmond Tutu today openly defied the government's ban on political funerals for the first time, then interposed himself between black mourners and white security forces to prevent a violent confrontation over the ban.

Tutu's personal intervention and painstaking negotiations with police defused a situation in which a bloody showdown had appeared inevitable. Dozens of armored vehicles and hundreds of heavily armed soldiers and police had encircled an angry crowd of about 1,500 mourners and a senior police officer had ordered the crowd to disperse only moments before Tutu stepped in.

The Anglican bishop, who has emerged in recent weeks as the most influential advocate of restraint in South Africa's black community, convinced police to supply seven buses to transport the crowd to a local cemetery for the burial of a 16-year-old victim of previous unrest. He then persuaded the youngsters to board the buses and conduct themselves peacefully.

Meanwhile, police in the Orange Free State town of Brandfort raided the house of Winnie Mandela, wife of imprisoned black nationalist leader Nelson Mandela, arresting 30 people after firing tear gas and rubber bullets into a crowd they said had thrown rocks at them outside the house. It was one of several incidents of unrest reported today outside the areas affected by government's declared state of emergency.

Tutu, who is bishop of Johannesburg, came to this sandy, wind-swept black township east of the city this morning to preach at a funeralfor Elizabeth Khumalo, 16, one of the victims of violence at a previous funeral.He addressed mourners in a tent in her front yard.

Tutu condemned the regulations, announced by South Africa's white minority government last week, that prohibit any mention of political issues at funerals for unrest victims. He violated the ban today by preaching against the restrictions and against the government's emergency decree, which took effect July 21.

Citing the Apostle Peter's defiance of the high priest of Jerusalem in the New Testament, Tutu told the crowd, "I do not want to defy the government. But the Scriptures state quite clearly when there is a conflict between the law of God and the law of man, we must obey God and not man. And so at funerals I will continue to preach the gospel."

"I don't want to go to jail," Tutu added. "But if I am to go to jail for preaching the gospel of our Lord Jesus Christ, then so be it."

The bishop also made an emotional plea to the government to allow blacks to freely conduct funerals for unrest victims.

"Please allow us to bury our dead with dignity," he said. "Please do not rub our noses in the dust. We are already hurt; we are already down. Don't trample on us.

"We are human beings; we are not animals. And when we have a death, we cry like you cry."

Just before Tutu spoke, three white policemen entered the yard of the house and hustled a young black man wearing a "Release Mandela" shirt into a green station wagon. One of the policemen aimed a shotgun at an angry crowd that drew near the car as it pulled away.

Witnesses identified the man taken prisoner as Aubrey Nxumalo, a local activist who they said had long been on a police list for detention.

"We can see how bloodthirsty these soldiers are," Steve Mochechone, a minister of the International Assembly of God, told the crowd after the incident. "We should not be so angered that we lose our heads."

Tutu also preached restraint, saying "I don't want us to provoke people unnecessarily. You are young . . . don't do anything which will give the system a chance to act against you."

As he finished, police using a bullhorn ordered the mourners outside the house to disperse.

Tutu then rushed to a nearby sandlot where police had massed to plead for a compromise that would allow the crowd to attend the burial. For 20 minutes the purple-robed bishop huddled with the blue-fatigued senior officer while two Army helicopters circled over the crowd.

Tutu came back with a commitment from Nel to seek buses so that the mourners could go to the cemetery without violating the restriction against funeral processions on foot.

A half hour later, seven buses supplied by the local town council pulled up and the confrontation was defused. There followed the incongruous sight of a black Nobel Prize winner and a white police lieutenant colonel overseeing the loading of the buses and directing traffic.

There was a far different conclusion to the episode outside the Mandela house in Brandfort this morning while Mrs. Mandela was in Johannesburg.

According to the police, 50 blacks gathered in front of the house after a store was looted and a school boycotted. The crowd was armed with knives, axes, picks, bricks and other weapons, police said, and they threw stones and a gasoline bomb at police after being ordered to leave.

They were then dispersed with rubber bullets and whips, and tear gas was fired into the Mandela house where some had taken refuge. Police said seven gasoline bombs and about five quarts of the fuel were found in the house.

A spokesman for Mrs. Mandela's lawyer said her sister had been arrested and her house "broken into" by police. She said the situation in Brandfort tonight resembled "a big war zone" with police and soldiers patrolling the area.

Winnie Mandela is a "banned" person under South African law who is not allowed to speak to reporters and has been remanded to the remote Brandfort area by the government. Friends said she had been in Johannesburg today for medical treatment.

Meanwhile a wave of violence continued to sweep through black townships near Durban, where activists are protesting last week's slaying of Victoria Mxenge, a prominent black civil rights lawyer. Durban is not one of the districts designated under the emergency decree but has been the scene of growing violence.

One man was shot dead by a policeman at Kwamashu township, while 17 preschool children suffered minor injuries when students stoned a school bus in Lamontville.

The treason trial of 16 black and Asian civil rights leaders in the city of Pietermaritzburg entered its second day with the lawyer for the defendants charging the government was resorting to McCarthyism and "guilt by association" in its case. The lawyer, Ismail Mahommed, conceded his clients were "antagonistic toward the state," but denied they had engaged in treason.

Outside the courthouse, a student boycott of township schools continued and police reported stone-throwing incidents in which eight people were injured and police used tear gas, rubber bullets and whips.