JOHANNESBURG, JAN. 31 -- A clash between black factions left eight people dead and dozens injured a day after African National Congress leader Nelson Mandela and Inkatha Freedom Party chief Mangosuthu Buthelezi called on their supporters to end virtual warfare between them, police said today.

In another development, officials said four men who -- with Mandela's wife, activist Winnie Mandela -- face kidnapping and assault charges have jumped bail. A senior judicial official said the escape of the four could put Monday's trial in doubt. {The attorney general of the Witwatersrand region, Klaus von Lieres und Wilkau, said a decision on whether to proceed with the trial would be made Monday, the Reuter news agency reported.}

The defendants were charged in connection with the murder of 14-year-old black activist Stompie Seipei, who was killed by a member of Winnie Mandela's bodyguard in 1989.

According to police, members of rival black groups fought with spears, knives and guns Wednesday night and burned or damaged 150 houses near Umgababa in eastern Natal Province, according to police reports. Police said the clash involved ANC and Inkatha followers.

On Tuesday, Mandela and Buthelezi met for the first time in 28 years and appealed for an end to years of fighting between their supporters.

"Everyone's hopes were raised, especially in the manner in which the talks were conducted and the accords were made," Buthelezi told the South African Broadcasting Corp. "So I am very concerned about it as it now compounds our problems."

Mandela, who was visiting Namibia on Thursday, told reporters it would take time to spread the peace message throughout the country.

The ANC has previously accused police of instigating violence and siding with Inkatha, a charge denied by the government and Inkatha.