President Cyril Ramaphosa said on Tuesday his early morning walks gave him time to think about his cabinet amid growing speculation about its composition and the future of the finance minister.

In his state of nation address on Friday, Ramaphosa strongly hinted at a cabinet shake-up when he said he would review the make-up and size of government departments.

Investors are watching closely to see if Finance Minister Malusi Gigaba, who is due to deliver the budget speech on Wednesday, keeps his job.

"This is the time to walk, to reflect even about cabinet and all that," he told reporters on television news channel eNCA during his walk in response to a question on whether there was time to shake up his cabinet ahead of the budget speech.

Ramaphosa was sworn in as head of state last Thursday after his predecessor, Jacob Zuma, reluctantly resigned after a nine-year tenure blighted by scandals, policy uncertainty and stagnant economic growth.