"You have arrived in hell."

With those mocking, ominous words, a black police sergeant would welcome detainees to the seventh floor of this city's gleaming Louis le Grange police headquarters, where, according to affidavits filed by former prisoners, they would be systematically beaten and humiliated.

There are 134 sworn statements from detainees and relatives in the lawsuit filed here last September by a white, 25-year-old prison doctor named Wendy Orr. Together they paint a stark portrait of alleged police terror in the weeks after the South African government declared a state of emergency and police began large-scale early-morning roundups of activists in this city's seething black townships.

Dozens of the detainees said they were punched, whipped, kicked and tear-gassed either during arrest or at police stations where they were taken. Many of the victims said they were forced to run a police gantlet at the stations.

But the most serious abuse, as depicted in the affidavits, took place at the newly built police headquarters building, which is named after South Africa's law and order minister.

"They called us their customers," said Dennis Neer, 36, a well-known trade union leader who was one of the earliest detainees, in late July. He said he was beaten with whips, punched in the face, kicked and had his toes stomped on by police who accused him of helping burn down a black policeman's house.

Neer said his breaking point came when police placed a stick between his handcuffed hands and twisted it. He pleaded with them to stop and "confessed" to whatever they told him.

Neer was among the detainees examined in prison by Dr. Orr, who said she found their bruises and other injuries consistent with their complaints of torture. Altogether, Orr said, about half of the activists she examined in the early weeks of the state of emergency were arriving at the prison with welts and blisters in unusual places, cuts, bruises, perforated eardrums and facial injuries. In seven weeks, she said, she found 153 detainees whose wounds were "inconsistent with injuries inflicted in a lawful manner."

Early last month the police submitted affidavits to the court denying the charges. Divisional Police Commissioner E.S. Schnetler said many of the detainees' injuries could have been received while resisting arrest or even imposed before arrest by "kangaroo courts" operated by black militants in the townships.

He called "unjustified" the impression given by the plaintiffs in the case that "police were waging a war of unbridled force" against black activists.

"I do not suggest that single cases of transgression do not occur," Schnetler's affidavit said, "but this is no reason for unfounded, generalized allegations to be made against the police."

When Orr consulted a lawyer about her findings and the refusal of her medical superiors and prison officials to investigate the prisoners' complaints, the lawyer said she had two choices: she could forget the whole thing and, like her fellow physicians, carry on with treating the prisoners. Or she could go to court, reveal what she had seen and seek an injunction against further assaults by the police. If she chose the latter, she was told, she undoubtedly would lose her job.

Orr became the first prison doctor to go to court against the police and won an unprecedented temporary restraining order against assaults by police in eastern Cape Province. In the process, she helped cast a spotlight on one of the darkest corners of this white-ruled society.

Charges of torture have surfaced continually since the early 1960s, when South African police first began using their broad powers to detain political opponents indefinitely without charge. But in the months following President Pieter W. Botha's emergency declaration last July, nearly 8,000 persons have been arrested -- eight times as many as in all of 1984.

One result has been a flood of new allegations of beatings, electric shock and other torture.

"There's no question" that cases of abuse and torture have increased since the emergency, said Jonathan Gluckman, a senior pathologist often called in by families to examine injured detainees. He said he has had 30 to 40 cases during the past seven months, more than he usually sees in a year.

At least 17 court cases on behalf of 83 plaintiffs were brought last year concerning allegations of assault by police against detainees, according to the Detainees' Parents Support Committee here. Most, like Orr's, are still pending.

In addition, researchers for the Institute of Criminology at the University of Cape Town last September reported "very strong evidence that torture is commonly practiced in South Africa." Their 2 1/2-year study was based on interviews with 176 former detainees, 83 percent of whom reported some form of physical abuse by authorities.

As in the Orr case, a handful of South African judges have reacted to the new allegations by issuing sweeping orders barring police violence against detainees. Yet white South Africa generally has reacted to this avalanche of new data with a collective shrug.

There have been few cries for an independent inquiry or a shake-up in the ranks of police. As her lawyer predicted, Orr was suspended from her prison duties the day after she filed suit. She since has been honored in certain quarters, ignored in most others. Meanwhile, new reports of brutality and assault surface weekly.

Critics contend that the government feels compelled to grant police a free hand, even though their actions sometimes undermine official initiatives and South Africa's image abroad. The police, they contend, represent a rightist constituency -- "the Conservative Party in uniform," as one analyst put it, referring to a white splinter party -- that Botha cannot afford to alienate.

But the lack of uproar over torture also suggests a profound moral ambivalence -- as well as callousness, critics say -- that lies at the heart of this white society: a desire to appear as a civilized, western nation where human rights are respected clashing against the fear of black revolution and the determination to crush it by any means.

"People who don't agree with the system are considered traitors and therefore not entitled to the normal protection of the law," says Helen Suzman, an opposition member of Parliament. "The government simply turns a blind eye because it says we have to give the police the means of finding out information to track down traitors. When you equate survival with patriotism, it's easy for the ends to justify the means."

South African police spokesman Col. Leon Mellet would not comment on specific cases in litigation, but referred a reporter to 1982 regulations prohibiting torture and providing for medical examinations of detainees. Police generally have argued that most torture charges are part of a communist-inspired propaganda campaign to discredit and undermine law and order.

Over the years, South African judges generally have been inclined to agree. A 1981 judicial commission on security legislation upheld the police contention that detention was needed to cope with the threat to South Africa from Soviet-supported groups such as the outlawed African National Congress.

Detention without trial "is a very drastic measure," the commission concluded, but "information obtained from persons in detention is the most important and, to a large extent, the only weapon of the police for anticipating and preventing terroristic and other subversive activities . . . . It is essential to retain this measure."

When it comes to allegations of torture, judges also have tended to believe the police version. "I'm not saying it doesn't happen here, but a lot of things are alleged that just are not true," said Christoffel Eloff, a Transvaal Supreme Court justice who has presided over many security trials. The percentage of cases of police abuse, Eloff contended, is "very, very small."

In testimony supporting Orr's suit, the "helicopter" is one specific form of torture described in several of the affidavits. Leslie Mangcotywa, 25, says he was forced to crouch and a long stick was placed behind his knees. His arms were passed under the stick and his hands cuffed in front of his shins. Then he and the stick were lifted and suspended between two tables.

Mangcotywa says he slipped upside down and blood rushed to his head, while his arms, wrists, knees and back ached from the strain. Two policemen allegedly took turns hitting him on the buttocks with a whip.

"If they did not like any of my answers, I would be hit," he recalled in his affidavit. "I pleaded with them to release me. I screamed when I was hit and as the pain became quite excruciating, I began to cry."

Mangcotywa said the police tied a cloth over his mouth to muffle his screams. They would remove it to hear his answers, then replace it and hit him again.

Ivy Gcina, 49, an activist in a group affiliated with the United Democratic Front, the country's main legal opposition group, said she was assaulted and sprayed with tear gas during her interrogation. While her questioners took a break, she said, a policewoman took her to another office to hide her. The woman pretended to hit Gcina when another officer came into the room. When he took a baton and hit Gcina, she said, the policewoman fled from the office.

Even relative celebrities said they were not immune from torture. Mkhuseli Jack, 28, leader of the shopping boycott that virtually shut down Port Elizabeth's central business district for five months last year, said he was given the "helicopter" by police who insisted that he phone other activists and call the boycott off.

Jack said that after he was tortured, in early August, a police warrant officer named Niewoudt warned him not to file a complaint or he would "disappear." Jack said he later was visited by a police colonel investigating complaints of torture. Jack said he wanted to file charges but first wanted to see a lawyer.

A few days later, Jack said in his affidavit, he was taken back to the police station, where officer Niewoudt "said he was going to deal with me and kill me on the spot." Niewoudt calmed down, Jack said, only when Jack told the policeman that he had not filed charges.

At least 64 detainees have died in police custody since 1963. Most were said to have committed suicide by hanging themselves, while several allegedly fell or jumped out of open windows at police headquarters in Johannesburg. Two died during one month in 1969 from injuries supposedly sustained from slipping in the bathroom.

One of the most publicized deaths was that of Dr. Neil Aggett, a trade union official who allegedly hanged himself in 1982. At the subsequent inquest it was revealed that Aggett, the first white to die in detention, had complained of being assaulted and electrically shocked by police and had been interrogated continuously for more than 60 hours shortly before his death. Nonetheless, the magistrate ruled that police were not responsible.

Only one policeman ever has been convicted for a detainee's death, a sergeant who received a 10-year sentence in 1984 for shooting a prisoner in the head. He has remained on bail pending appeal.

Besides Aggett's, the most publicized death of a detainee was that of black consciousness leader Steve Biko in 1977. Officials at first claimed that Biko died from a hunger strike. But an inquest later ruled that he died of head injuries probably sustained in a scuffle with police. Nonetheless, the magistrate ruled that no one could be held responsible, although eight years later two state doctors were disciplined by the national medical council for negligence in failing to treat Biko's injuries.

Biko's death greatly embarrassed South Africa overseas and led to a United Nations arms embargo. But no policeman ever was punished for it -- indeed, several of those involved later received promotions.

"My personal view is that if a few heads had fallen after Biko's death, the message might have gotten through that we think this kind of activity is wrong," conceded Justice Eloff.

Orr's lawsuit is particularly significant because it is taking place in the same city where Biko sustained his fatal injuries. Orr worked under the same doctors, Benjamin Tucker and Ivor Lang, who were implicated by their negligence in Biko's death.

At first Orr, who began work in January 1985 to pay off a state scholarship, oversaw only long-term criminal offenders. But beginning in August -- 10 days after the emergency declaration -- she was assigned to examine daily the burgeoning numbers of detainees.

She says her concern began to mount around Aug. 16, when she examined a group of about 170 prisoners. Roughly half complained of assaults and had marks, cuts and bruises to support the complaints. She made notations about the assaults and requested an investigation on each prisoner's yellow medical card.

There was another mass intake on Sept. 4 of 360 detainees. Again, about half told Orr that they had been assaulted.

The next day Orr took her findings to Lang, her immediate superior, who phoned his boss, the regional health director for the eastern Cape. According to Orr, Lang told her she should simply make copies of the yellow cards in case any of the prisoners filed suit. But when she went through the files she found that many cards were missing and others were incomplete.

Orr says she was called to the office of Brigadier Hills, the prison commander. He told her that his department was not responsible for investigating such complaints and that the police also would not investigate because they believed that under the state of emergency they were immune from prosecution. She says she was told to stop writing requests for investigations on the cards.

"Nobody seemed prepared to do anything more than make sure their noses were clean," she recalled. "They weren't prepared to make waves."

The daughter of a Presbyterian minister and a social worker, Orr said she was not willing to remain silent. She stunned authorities by going to court and winning a sweeping restraining order against police. Her lawyers were particularly pleased that the court order authorized them to interview and solicit affidavits from those still being held.

Orr was informed the day after she appeared in court that she would no longer be allowed to visit the prisons. This was done for her own protection, health officials later claimed, because of "strained relations" between her and prison officials and police. Left with little to do, she finally quit her job in January and moved to Johannesburg to start work at a health clinic serving a black township.

Most observers here do not expect the Orr case to end police abuses -- but for some detainees it has helped restore some of the self-respect and dignity that the alleged torturers sought to strip away.

"To be honest, I don't think this lawsuit will stop the police for very long," said Ihron Rensburg, who submitted an affidavit alleging that he was tortured during the two weeks he was held in July and August. "But something had to be done. We have to make everyone aware of what's happened, even if it means sticking your own neck out."