Two witnesses at the kidnap and assault trial of Winnie Mandela refused to give evidence on Wednesday, saying they were frightened.

"I fear for my life," said Barend Mono, 21. "If I proceed to give evidence I don't know what will happen afterwards."Earlier, Kenneth Kgase, 31, told the Rand Supreme Court in Johannesburg he was too scared to testify after a third prosecution witness, Gabriel Mekgwe, was kidnapped by unknown men from the safety of a Soweto church hostel over the weekend.

"I am very, very scared," Kgase told Judge M.S. Stegmann. "As soon as the trial is over, there is no guarantee of any protection of any sort."

The judge said he would decide Thursday on whether the witnesses should be obliged to testify.

Mono and Kgase face jail terms if they refuse to obey the judge's order to enter the witness box. But Kgase's lawyer, Paul Kennedy, told the court even this would not persuade his client to speak out.

The refusal of the witnesses to speak out severely jeopardizes the state's case against Mandela, wife of African National Congress deputy president Nelson Mandela, and her three co-defendants.

Prosecutor Jan Swanepoel said that if his star witnesses dried up, he might be obliged to postpone the trial until May or June in an effort to find Mekgwe.

The prosecution alleges Kgase, Mono, Mekgwe and 14-year-old Stompie Seipei were kidnapped two years ago on the orders of Mrs. Mandela.

It accuses Mrs. Mandela and her associates of holding the four anti-apartheid activists hostage for several days at her house and says they were brutally beaten, kicked and whipped there.

Mandela and her co-defendants deny the charges, saying the activists were taken from the shelter without coercion because they were being molested by the church minister.

Seipei was found dead a few days after the alleged abduction. Last year, the former leader of Mrs. Mandela's bodyguard was sentenced to death for the murder.

Mrs. Mandela's lawyer, George Bizos, told the court that Mekgwe's disappearance was "not of our client's making."