South Africa's embattled President Jacob Zuma on Thursday served a court notice to block a watchdog from releasing a report into allegations that he was involved in corrupt activities, his spokesman said.

"That is true, there is an application for an urgent interdict," Bongani Ngqulunga told AFP a day before Public Protector Thuli Madonsela was expected to release her report into allegations that Zuma let a wealthy business family choose ministers.