Nine people living in northern Namibia (Southwest Africa) have signed sworn statements alleging that they were mistreated, assaulted and given electric shocks while in the custody of South African security police.

The affidavits, which legal experts here described as one of the fullest documentations of alleged abuses of detainees by security police, were entereed as evidence before a South African court in Windhoek. Namibia, Wednesday as part of a request for an injunction restraining police from mistreatment of a man now in police custody.

Brigadier Vic Verster, divisional commander of police in Southwest Africa, said today that the "allegations of police torture are "absolutely and completely false. I most vehemently deny the allegations."

The allegations come at a time when South African security police are under intense criticism for their actions in the Steve Biko case and at a time when negotiations leading to the independence of Namibia, which South Africa now rules, are in a crucial stage. Biko, leader of the black consciousness movement in South Africa, was the most widely known of some 20 blacks to die while in detention.

The talks on Namibian independence have created a "new political mood" in Southwest Africa observers say, citing this as one reason why the ninepeople citing the affidavits chose to risk retaliation from the security police.

Southwest Africa bordered on the north by Angola, is administered from Pretoria under an old League of Nations mandate that the United Nations had declared illegal. The five permanent members of the U.N. Security Council have been negotiating with the South African government and the U.N.-recognized liberation movement, the South West Africa People's Organization, on a plan that would lead to independence next year. South Africa has made significant concessions to reach an agreement wit SWAPO, which is waging a guerrilla war from bases in Angola.

Colin du Preez, the Windhock attorney who gathered the statements from the former detainees, said the nine depositions are "only the periphery of what we've got." Referring to several more as yet unsworn statements alleging police abuse, du Preez attributed the willingness to make the sworn allegations partly to confidence that South West Africa "will soon be an African-ruled country." He also said the accusors were encouraged by the "safety in numbers."

Among the nine persons alleging police torture are students, farmers, a Lutheran pastor, nurse and a village headman.

When Raula Shinbode, an assistant nurse at the Roman Catholic Hospital at Windhoek was arrested April 15, she reportedly was told it was because she "was a friend of the terrorists."

In her deposition, she says she "was suspended by my arms, with my back against a wall and my arms above my head, tied individually . . . in such a manner that my feet were completely clear of the ground."

She was kept hanging for two hours, received electric shocks about four times and then lost conciousness, she said, adding that she got back in her cell and this continued for 15 days.

Naftali Shigwedha, 51, whose affidavit was marked with his fingerprint because he cannot write, was accused by the police of having slaughtered an ox to feed some SWAPO guerrillas.

He said he was suspended on a metal bar, upside down, and was given electric shocks on his temples. "I cannot coherently describe the extreme pain I suffered, and words are insufficient to describe the feeling of one's body being torn apart. I cannot say for how long I was shocked, but it felt like an eternity."

The nine sworn statements are supporting evidence in a request by Franciscus Petrus, 58, a driver employed by the city of Windhoek. He is asking the courts to issue an urgent order to Police Minister Jimmy Kruger and to the head of the security police in Oshakati in Southwest Africa, Col. Willem Schoon, forbidding them or anyone under their command from using pressure, duress, assaults or electric shock on Petrus' 21-year-old son, Bernardus, who is being held under the Terrorism Act.

In the request, Petrus said his lawyers have asked the South African courts to prevent the police from doing something the police insist they do not do - use physical violence in questioning detainees.

Brigadier Verster attributed the allegations of police brutality to the activity of Communists.

"You know my dear lassie . . . the Vietnam war was enormously, tragically lost because the U.S. soldiers were fighting with one hand tied behind their backs. That one hand was the mass media that had turned against its own kin," Verster said in a telephone interview.

"You can go back into the annals of the suppression of the avalanche of communism from the end of World War II and you will find that the bastions, the pillars representing law and order are forever the deliberate targets of professional do-gooders. So it is no surprise to us whatsoever (to have) this deluge of allegations of police brutality, of jack-boot activity - all jargon that is taken out of Pravda."

Young Petrus reportedly was seen by one of his friends as he got out of a police van outside a police station. The friend Tauna Hatuikulipi, said in a sworn statement that Petrus' face was swollen and his eyes puffy and red, adding that "it was obvious that he had been assaulted on the face."

Col. Schoon of the police in Oshakati told the court that Petrus had not been assaulted and he pleged that nothing would happen to him, according to du Preez. Schoon said a magistrate would visit Petrus weekly, not every two weeks, as is required by law, and produced a picture of Petrus that the judge later said was a photograph of "a happy, healthy man."

The judge ruled that an urgent injunction was unneccessary and the ruling is being appealed.

Although South African authorities found the security police tree of any blame in Biko's death. du Preez said the Petrus case was being pressed because "this sort of thing should be settled once and for all . . . The police say the allegations are exaggerated, cooked up . . . and the churchmen and the people say it's really happening. Is it or isn't it?"