SOUTH AFRICA'S PRESIDENT ENDS 30-YEAR BAN ON MANDELA GROUP; SAYS IT IS TIME FOR NEGOTIATION
LEAD: President F. W. de Klerk today lifted a 30-year ban on the African National Congress, the movement that has been fighting to bring down white minority rule in South Africa, and promised that Nelson Mandela, who has been imprisoned for nearly 28 years, would be freed soon.