By RACHEL L. SWARNS
JOHANNESBURG, April 25 - After weeks of whispers about political jousting and maneuvering within the governing African National Congress, the minister of safety and security has accused three leading members of the party of plotting to oust President Thabo Mbeki.
The announcement that the three, Cyril Ramaphosa, Tokyo Sexwale and Matthews Phosa, all prominent businessmen, were under investigation was front-page news today and it left some government officials reeling. All three were fighters for liberation during the apartheid regime.
Mr. Ramaphosa and Mr. Sexwale have long been viewed as potential rivals to Mr. Mbeki although both men have left politics to pursue lucrative careers in business.
Opposition politicians quickly condemned the investigation as an attempt by Mr. Mbeki to neutralize opponents who might be tempted to deny his hopes for a second term. A.N.C. officials denied that the probe was politically motivated.
The investigation became public on Tuesday night when Steve Tshwete, minister of safety and security, announced on national television that the three men were believed to be running a disinformation campaign against the president. Of particular concern, Mr. Tshwete said, were rumors charging Mr. Mbeki with orchestrating the assassination in 1993 of Chris Hani, the revered South African Communist Party leader.
Two right-wing whites were convicted of killing Mr. Hani, who was one of Mr. Mbeki's rivals for the position of deputy president to Nelson R. Mandela.
Mr. Tshwete said rumors linking President Mbeki to the death of Mr. Hani might have led Mr. Hani's supporters to turn on the president.
"There are sworn affidavits of a plot and disinformation campaign and we have to investigate to see to what extent does it compromise the safety of the president so that we can take the necessary precautions," Andre Martin, a spokesman for Mr. Tshwete, said in an interview this afternoon.
Officials refused to divulge further details of the reported plot today, but Mr. Tshwete said that the government was bolstering Mr. Mbeki's personal security.
The allegations are the most recent hint of factional fighting within the party. Mr. Mbeki, who succeeded Mr. Mandela in 1999, has been viewed as increasingly vulnerable in A.N.C. circles. Polls indicate that his popularity has slipped, and he has stumbled in his handling of the AIDS epidemic and some other issues.
In a surprise public statement earlier this month, Deputy President Jacob Zuma unexpectedly denied rumors and "unverified, so-called intelligence reports" that he might stand for the position of A.N.C. president.
Earlier this year, Winnie Madikizela-Mandela, president of the African National Congress Women's League, denied that she was spreading malicious rumors about Mr. Mbeki. Mr. Sexwale and Mr. Phosa vehemently denied today that they were plotting against the president.
Mr. Ramaphosa, who was once the A.N.C.'s secretary general and is now chairman of a powerful media and telecommunications company, helped lead the negotiations that brought an end to all white rule and was Mr. Mandela's first choice as a successor.
Mr. Sexwale, who was imprisoned by the apartheid government and later ran the provincial government that includes Johannesburg, "is more than satisfied" with running a black empowerment company with interests in diamond and platinum mines, his family said.
"Our country faces real and serious socio-economic problems, most of all poverty," the family said in its statement. "It is an unwarranted, precious time-wasting exercise to be diverted by gossip and rumor-mongering based on cooked-up stories."
Mr. Phosa, who served as an A.N.C. legal adviser under apartheid and led the province of Mpumalanga before moving into business, described the allegations as "insulting the intelligence of ordinary South Africans."
Leaders of the opposition party, the Democratic Alliance, describing the investigation as an abuse of government powers.
Mr. Mbeki declined to discuss the issue today, but in a TV interview on Tuesday, he urged the so-called conspirators to abandon their plotting and to declare their ambitions.