South Africa's Intelligence Minister has suspended three senior officials in the National Intelligence Agency, pending an investigation into the illegal surveillance of a business executive.

Minister Ronnie Kasrils suspended the Director General of the National Intelligence Agency and two other senior officials after an influential business executive lodged a formal complaint of unlawful surveillance.

Mr. Kasrils says told reporters in Pretoria that the officials were suspended pending the outcome of an official inquiry being conducted by the Inspector-General of Intelligence.

Business executive Saki Macozoma told a Johannesburg newspaper that he lodged the complaint when he became aware of the surveillance, which he described as overt and "in your face".

The alleged surveillance of Mr. Macozoma comes against the backdrop of an aggressive factional dispute within the ruling African National Congress after the firing of former deputy president Jacob Zuma, who has presidential aspirations.

Mr. Macozoma is a powerful member of President Thabo Mbeki's inner circle and has been touted as a potential successor to Mr. Mbeki when he steps down in 2009.

Since he was fired two months ago, after a judge found his relationship with his convicted financial advisor was corrupt, Mr. Zuma has himself been charged with two counts of corruption. His supporters demanded the charges be withdrawn, saying they are part of a campaign to prevent him from becoming president.

His supporters have also publicly burnt ANC t-shirts bearing Mr. Mbeki's picture and chanted slogans and songs in isiZulu which insulted Mr. Mbeki.

And even though he and Mr. Mbeki agreed to keep their dispute out of the public eye and to reign in their supporters, Mr. Zuma has continued to make public statements in which he makes thinly veiled denunciations of Mr. Mbeki. This week he spoke disparagingly of those he called "academic leaders" - Mr. Zuma never received a formal education but has been awarded honorary degrees.

Analysts have warned that if the National Intelligence Agency is drawn into disputes within the ruling party, or other political issues, it would pose a threat to the country's national security.