Despite international criticism of South Africa that resulted in a mandatory U.N. arms embargo last October, the use of detention without trial continues as an institutionalized way of intimidating asn shattering this country's black leadership.

An international furor followed the arrest of 40 black leaders and the banning of 18 black and civil rights organizations last Oct. 19. But there has been little notice that since then, almost four times that number of people have been detained for varying periods, that new black political organizations are emasculated as their leaders to jail and that outspoken black leaders continue to be banned.

Moreover, stories of police assaults and torture continue to be told by detainees who are released. People who have been held under what is called "Section Six" of South Africa's antiterrorism law tell of being beaten, whipped and of having electic shocks applied to their heads while their hands and feet were tied together.

At the government inquest last month into the death of Lungile Tabalaza, who fell from the fifth floor window of a police station, last July, a witness told how he saw Tabalaza come out of a room with "tears in his eyes' shortly before his death. A policeman who accompanied him had wire in his hands.

The allegations of torture continue this year even after the unfavorable spotlight on police brutality during the inquest last November into the death of black consciousness leader Steve Biko.

In the first seven and a half months of this year 190 people were arrested and detained without trial under South African security laws, according to records of the South African Institute of Race Relations, the only independent body that keeps tabs on political detentions.

The office of Justice and Police Minister Jimmy Kruger said it was unable to say how many people have been arrested so far this year, but it did confirm that 118 people were arrested under security legislation in the weeks leading up to June 16, the second anniversary of the outbreak of black urban protest in 1976.

Some of the 190 people arrested this year were released after periods ranging from days to months, but according to institute records, 124 of them are still in detention. Of the black leaders arrested last Oct. 19, the records say, 28 have been freed while the detention orders of the other 21 have been extended until next July. This action, the black daily Johannesburg Post commented, confirms "the suspicions of those people in the international community - and at home - who seriously doubt the government's intention of abandoning its present course."

Police activity this year demonstrates that detention without trial is a tool readily employed to stave off any recurrence of the open black protest against the government's discriminatory policies.

Leaders of one black group, the Azanian Peoples Organization, were rounded up as soon as the group was formed last May. The chairman, Ishmael Mkhabela has been in detention since May 4.

Another target of the police this year has been the Roman Catholic Church's Young Christian Workers. Its national president, Phelco Magane, spent 85 days in detention and was the first of 30 in the group to be arrested. Six of them remain in jail. Only four have been charged - with actions that have nothing to do with the organization.

Many of those released from jail are essentially no freer than those who remain inside. Some, like Nyameko Barney Pityana, who was a cofounder with Bike of the black consciousness movement, were immediately served with banning orders prohibiting them from normal social contact after release.

YPityana fled to neighboring Lesotho recently. Others, like Soweto leader Nthato Motiana, are simply threatened with indefinite detention if they continue to speak out.

The prospect is that such police activity will continue. Asked how long detentions without trial at this level might go on, the deputy head of the security police, Johan Coetzee said, "As long as there is an East-West confrontation it will continue. As long as the communists are on the offensive and create organizations with nice sounding names like the 'Blanket Fund' or the 'Blood Fund'. . .we can do one of two things, surrender or fight."

Questioned about the torture allegations, Coetzee took from his briefcase an Amnesty International report on similar allegations made by Irish prisoners against the Royal Ulster Constabulary in Northern Ireland.

"Those police answered (the charges) the same way we do," he said. "We have people in a conspiracy who are ideologically committed to overthrowing the state and law enforcement agencies.Their job is to show the state is immoral and unjust so they say there perverted and immoral people in law enforcement agencies and create the image of a Nazi, jackboot organization."

"I've had New York policemen tell me they can't combat crime without using some force, like stepping on toes, and backing people against the wall," Coetzee added.

Superficially, the police have achieved what they set out to do: The segregated urban black residential areas are quiet.

"This quiet is taken by them as a sign they have triumphed," said one of those arrested Oct. 19 and recently released. "If people do anything now, of necessity it is on the quiet, because if it is in the open, they are likely to be harassed."

Meanwhile, Police and Justice Minister Kruger recently told a group of government supporters that "when I banned them, I knew these organizations would not fade away. They are always there, busy reorganizing and moving forward. Let me tell them directly - we are also always there, busy seeing that our country and our people are safe."