President Jacob Zuma on Tuesday downplayed the possibility of a cabinet reshuffle following months of speculation that he would fire some ministers after a failed bid to remove him as leader of the ruling party.

The president of Africa's most industrialised economy faced a revolt from inside the African National Congress (ANC) in November after an anti-corruption watchdog called for a judicial inquiry into alleged influence-peddling in Zuma's government.

Zuma also rattled markets in December 2015 when he fired his respected finance minister in favour of a relatively unknown member of parliament. The rand was again hit last month by speculation that Zuma could remove Pravin Gordhan as finance minister.

"I don't know, since last year this speculation has been there and nothing has happened. Just forget about it. I will tell you when I need to tell you," Zuma told reporters on the sidelines of an investor lunch in Cape Town ahead of his state of the nation address in parliament on Thursday.

Zuma has denied allegations that he granted undue influence to the wealthy Gupta family, who run a business empire from media to mining.

The watchdog's report focused on allegations that brothers Ajay, Atul and Rajesh Gupta had influenced the appointment of ministers. Zuma and the Gupta brothers have denied the accusations.

The 74-year-old Zuma's popularity has waned after a series of scandals, leading to the ANC's weak performance in last year's local government polls, its worst since the party took power in 1994.