JOHANNESBURG, FEB. 13 -- Two crucial state witnesses in the trial of Winnie Mandela said in court today that they were too scared for their lives to testify against her, leaving both the judge and the prosecution in a quandry over whether to continue the proceedings.

"I've got to make a decision between my obligation and my life," said Kenneth Kgase, 31. "I really want my life. I like my life."

Kgase referred to the alleged kidnapping Sunday by three men of Gabriel Pelo Mekgwe, the third principal state witness and alleged victim of a 1988 kidnapping and assault, for which Mandela and three others are standing trial.

"If people can remove someone who has been subpoenaed when the case is going on, then there is more than meets the eye. I think my life is at stake. I'm very, very scared," Kgase said.

Kgase and the other state witness, Barend Thabiso Mono, sought to convince Judge M.S. Stegmann of the Rand Supreme Court that they each have a "just excuse" for refusing to testify in the light of Mekgwe's disappearance.

Mono, 21, who appeared in court after Kgase, said he too has "fear for my life because I already see what has happened to {Mekgwe}."

Kgase, Mono and Mekgwe testifed in a previous trial that they were kidnapped in late December 1988 and taken to the Mandela home in Soweto where they were beaten in her presence and with her initial participation. Mandela is the wife of African National Congress leader Nelson Mandela, who was serving a life sentence in prison at the time of the incident.

A fourth colleague, "Stompie" Moketsi Seipie, was subsequently murdered, an act for which Jerry Richardson, a former bodyguard of Winnie Mandela, has been convicted and sentenced to death.

The testimony of the three youths clearly would be the core of the state's case against Mandela, who was not charged or asked to testify in the Richardson trial.

The judge is expected to decide Thursday whether the trial will continue or be postponed for several months.

Jan Swanepoel, the chief state prosecutor, said today that a postponement of the trial until May or June might be necessary to allow the police time to locate Mekgwe..

Swanepoel said there was strong evidence that Mekgwe had been kidnapped but added that he could not state so "definitely," noting that there was a "rumor" Mekgwe had telephoned from outside South Africa since his disappearance to say that he was well.

The Star, Johannesburg's main English-language newspaper, reported tonight that it had received a call from Harare, Zimbabwe, today from a man claiming to be Mekgwe. He said he wanted to meet Judge Stegmann, but the call was then cut off, the paper said.

The South African Press Association news agency reported tonight that it had received a phone call from someone in Harare who said he was Mekgwe and wanted to meet Swanepoel "anywhere in the world except in South Africa because I believe in South Africa I'm not safe.

"I am in Harare now and I feel very safe," the caller said.

If Judge Stegmann orders the two witnesses to testify, they are expected to refuse, even at the risk of up to two year's imprisonment.

Swanepoel seemed discouraged by the turn of events and made little attempt to convince Judge Stegmann that he should order Kgase and Mono to testify. At one point, he told the judge, "I have great sympathy for Mr. Kgase's situation."

When the judge suggested that the prosecution present its medical and forensic evidence, Swanepoel replied that he thought it would be "a waste of time" because his case was built around the testimony of Kgase, Mono and Mekgwe.

Swanepoel elicited an assurance from Kgase that he would testify if Mekgwe was found unharmed, but Mono was more guarded in his response.

Most of today's proceedings were taken up by arguments over how to interpret the term "just excuse" and whether fear of reprisals from township supporters of Mandela was sufficient grounds for refusing to testify.

"I have to balance {Kgase's} interests with the interests of justice," Stegmann said. Allowing "lawless elements outside court" to "stop the truth from coming out threatens the very foundation of the administration of justice. That cannot be tolerated."

The judge asked whether the two remaining state witnesses would be willing to be taken into police custody to protect them during the trial and possibly for a "cooling off" period afterward. Swanepoel agreed that there are "certain farms" that the police use as safe houses, but he did not ask the judge to provide such protection.

Both Kgase and Mono said they preferred to remain under the protection of the Methodist Church and Legal Resources Center and doubted police protection offered any long-term safety.

The Methodist Church had provided a safe house in the northern suburbs of Johannesburg for all three witnesses. Mekgwe missed a ride and failed to return to the house Sunday night. He reportedly was taken from the same Methodist Church in Soweto where he allegedly was kidnapped by Mandela and her accomplices more than two years ago.