The assault and kidnapping trial of Winnie Mandela, wife of black leader Nelson Mandela, recessed Tuesday with prosecutors saying the disappearance of a key witness had left two others too frightened to testify.

"The witnesses are too scared to testify and may therefore refuse to testify," chief prosecutor Jan Swanepoel told a hushed Rand Supreme Court.The witnesses are three of four youths kidnapped and beaten in December 1988. Mrs. Mandela is suspected of involvement in the incident.

The fourth youth, 14-year-old James Stompie Moeketsi Seipei, was killed in January 1989 by Mrs. Mandela's chief bodyguard.

Judge Michael Stegmann recessed the trial until Wednesday to allow the prosecutor time to speak with witnesses Barend Thabiso Mono and Kenneth Kgase.

Swanepoel told the court he had subpoenaed the pair and could also have them arrested if they refused to give evidence but thought that would be "unfair."

Mrs. Mandela, 56, and three co-defendants pleaded not guilty Monday to four charges of assault and kidnapping.

Swanepoel told the court that witness Gabriel Pelo Mekgwe was abducted Sunday night, and police report no leads to his whereabouts.

But the Johannesburg Star reported Tuesday that Mekgwe left a Methodist Church hostel "with three African National Congress men. It is not known whether Mekgwe voluntarily accompanied the three, one of whom is a senior man in the ANC," the newspaper said. The newspaper did not identify a source for its story.