"A policeman's duty is to protect people, not kill them," said Louis le Grange, sitting with the erect posture of a guardsman in his office on the 16th floor of the massive modern building that houses the South African Cabinet in this legislative capital.

It would have sounded trite, except that during the past eight months the police force for which Le Grange is responsible as South Africa's minister of law and order has killed nearly 300 people in a determined attempt to quell disturbances among the country's voteless black majority.

Le Grange, 56, who looks like a middle-aged Clark Gable with his sleeked-down graying hair and trim mustache, is an enigmatic figure. He has presented an iron-man image while defending his police force against criticism, especially since 20 members of a black crowd were shot to death near the city of Uitenhage last month.

Blacks regard him as an ogre, and five of the eight political parties represented in Parliament have called for his resignation.

Yet in conversation in his office, Le Grange came across as a man who is concerned, if not exactly distraught, about the growing casualty list in the unrest, and he took pains to emphasize his belief that the police should use minimum force in all riots.

In public statements, Le Grange has assailed the major black political movement, the United Democratic Front, blaming it for instigating the unrest. He has called the group a front for the African National Congress (ANC), the black underground that is committed to trying to overthrow white minority rule by guerrilla struggle, and he has described the congress as a communist organization directed from Moscow. Last week his security police arrested three leaders of the United Democratic Front.

In the interview, Le Grange conceded that there was no pat explanation for the unrest, and that at least part of the cause was frustration among blacks at being excluded from the government's recent constitutional reforms.

"One cannot just blame a particular organization or individual," Le Grange said. "One must have a broader approach. I am not one of those who says it is just because someone is a communist, or a member of the ANC. I turn these things over in my mind and try to find solutions."

Political opponents also detect what they describe as two sides to the man.

"He defends whatever the police do almost as a matter of principle, yet whenever I discuss matters with him at a personal level I find him much more flexible and reasonable," said Frederik van Zyl Slabbert, leader of the liberal Progressive Federal Party, the main opposition in the white-dominated Parliament.

Helen Suzman, the leading civil rights figure in Parliament, whose frequent appeals for political prisoners have brought her into close contact with Le Grange, said the same.

"He has a blind loyalty to the police," she said. "But there is also a reasonable side to him to which one can appeal.

A sense of paternalistic protectiveness toward the police -- not just law-enforcement officers but the white Afrikaners' first line of defense against a host of perceived enemies and conspirators -- is perhaps the key to this dichotomy in Le Grange's nature.

He has spent most of his life working with the police and he regards it as axiomatic that there should be a relationship of total loyalty and trust between them.

"He feels himself to be a father figure over the police force," said his press secretary, Col. Leon Mellet.

Le Grange's father, a country shopkeeper and farmer, died when he was 11 and the lad, youngest of a family of five, put himself through college, studying part-time while working as a prosecutor in the magistrate's courts in the western Transvaal town of Potchefstroom. His contact with the police began then.

After graduating, Le Grange joined a law firm and specialized in trial work. He won a parliamentary seat in 1966, and immediately specialized in the affairs of the departments of justice, police and prisons. Later he became deputy minister of police and six years ago became minister of law and order.

"I have lived with the police for 38 years," Le Grange said with pride. It has rubbed off on him visibly. He is 6 feet 4 and has acquired the erect bearing of a military man. His favorite sport is marksmanship, and he captained a junior national team in 1970.

"He shows an individual concern for the police," said Mellet. "The men love him."

And he loves them. "I understand a policeman," Le Grange said in the interview. "I know how his mind works. The average policeman is the most loyal servant a government could wish to have . . . . I have known some of the best characters that one could find in any nation among the police.

"But they are also very sensitive," he added. "They are entitled to be respected for what they are -- loyal, reliable people who are serving the public."

"The trouble with Le Grange," said Suzman, "is that he has a blind confidence in his underlings and accepts without question what they tell him. I think this is very dangerous."

Not so, said Mellet. "He is very sensitive to criticism. He questions things. He always tries to establish the real truth about things."

The test may come when Judge Donald D. Kannemeyer, who is conducting the inquiry into the Uitenhage shootings, presents his report within the next few weeks. Testimony at the inquiry has revealed that Le Grange's first report to Parliament of what happened was incorrect. His loyal police have taken the blame. They briefed him incorrectly, Police Commissioner Johan Coetzee told the commission.

The inquiry has yielded other evidence damaging to the police. They were under orders not to take tear gas and rubber bullets with them on the day of the shooting but only lethal weapons. They had orders to "eliminate" any rioter seen throwing a bomb filled with gasoline or acid. Le Grange did not want to talk about Uitenhage while the inquiry was still in progress, but the views he expressed seemed to conflict with these orders and much of the evidence on what happened.

"My approach is that the police should try to calm down a situation as effectively and quickly as possible without the use of force," Le Grange said.

"They should talk to the people first of all," he went on. "If that doesn't work and force must be used, then I am adamant that it must be the minimum force necessary for the occasion. Everything possible must be done to ensure the absolute minimum loss of life and minimum injuries."

This approach, the law and order minister said, had resulted in his being accused in some quarters of being "too soft." He explained that "quite a few members of the public have criticized me."

"But I would rather be criticized for that than be blamed for using unnecessary force," he added.

Did the killing of nearly 300 people not indicate an excessive use of force?

"No, I don't think so," Le Grange replied in a reflective tone. "It is unfortunate, very unfortunate, that we have had that number of lives lost, but you must keep in mind that we have had to do with large crowds and sometimes very violent crowds; people who attack the police with stones, bricks, petrol gasoline bombs, even guns. We have been shot at. In the light of that I don't think our use of force has been excessive."

What of the order, ostensibly issued with the minister's tacit approval, that went out from police headquarters on March 19, two days before the Uitenhage massacre, instructing riot squads to "eliminate" anyone seen throwing a gasoline or acid bomb? Was that not excessive?

"I think the use of the word 'eliminate' was unfortunate," Le Grange replied. "I am on record as saying that no one must be allowed to throw a petrol bomb at a policeman. Stern action must be taken against anyone who does, but 'eliminated' was an unfortunate choice of word." Le Grange appeared unconcerned about the calls for his dismissal. President Pieter W. Botha has declared his support for him and the tough methods used by the police. A pile of telegrams and letters on his desk testify to the fact that white South Africans like tough police ministers.

"I don't think for a moment that my position is in jeopardy," he remarked, permitting himself the smallest of chuckles.

One reason he will stay in his job, a South African newspaper has suggested, is that he is politically indispensable to President Botha.

Again it is that question of loyalty. The police are a conservative force and most of them dislike Botha's policy of cautious reforms.

But, the mass-circulation Johannesburg Sunday Times suggested, the police are loyal to Le Grange because of his "knee-jerk defense of even their most questionable action," and Le Grange is unswervingly loyal to Botha.

"I wouldn't say I was indispensable," was Le Grange's cautious response to this. "What I would say, though, is that the president knows he enjoys my absolute loyalty and that of the police."