The divisive politician’s accusations came just months before the ruling ANC party’s year-end crunch conference where Ramaphosa is expected to seek a second term.
“Your president is corrupt. Your president has committed treason,” Zuma told a news conference in Johannesburg — his first since he ended his 15-month jail term earlier this month for contempt of court.
He was reacting to allegations earlier this year that Ramaphosa concealed a multi-million-dollar cash heist at his luxury farmhouse.
“No president should conduct private business while in office. It is inconsistent with the oath of office taken by (the) president,” he said.
“Our country’s problems are too big for a president who is busy hustling on the side.”
The scandal erupted in June after ex-national spy boss Arthur Fraser filed a police complaint, alleging that robbers broke into Ramaphosa’s Phala Phala farm in northeastern South Africa, where they found and stole $4 million in cash hidden in furniture.
– ‘President has failed’ –
Zuma said he wondered what would have happened had he been the one accused of hiding “millions of dollars hidden under my mattress”.
Fraser, seen as an ally of Zuma, alleged that Ramaphosa concealed the robbery from police and the tax authorities, and instead organised the kidnapping and questioning of the robbers, and then bribed them into silence.
The president has acknowledged a burglary but denies the accusations of kidnapping and bribery, saying he reported the break-in to the police.
He has also disputed the amount of money involved, and said the cash came from legitimate sales of game from his animal-breeding farm.
South Africa’s parliament this week opened a probe on whether the farm saga renders Ramaphosa impeachable or not. The police is also investigating the case, but Zuma said there was “silence of the many criminalities against the current president”.
The case has piled unprecedented pressure on Ramaphosa, who came into office on the promise of busting graft.
It also comes amid heightened heavy infighting within the ANC, ahead of a national elective conference in December.
The party is to hold internal polls to pick a new leader, who would then become the candidate for the next presidential election in 2024.
Zuma said the December conference “is going to deal with (Ramaphosa)” and decide whether the party wants him to stay. “Many people (are saying) that this president has failed.”
Another former president who succeeded anti-apartheid icon Nelson Mandela, Thabo Mbeki, also bemoaned the state of the ANC ahead of the December meeting.
“Our president is under a lot of pressure… around the matter of Phala Phala farm,” he told a separate meeting in Johannesburg.
Zuma became president in 2009 but was forced to leave office after nine years in favour of then vice-president Ramaphosa — last month he said he was ready to make a political comeback at the ANC party’s internal conference.
On Saturday he said if the party asked him to run for one of the top party positions, “who am I to say no?”
Support for the party of Mandela dropped below 50 percent for the first time in local elections last year, and the government is facing growing discontent over widespread poverty, unemployment and a prolonged power crisis.
Zuma is a divisive figure whose name resonates with graft for most South Africans but he remains a hero to many grassroots ANC members.
He is still facing separate corruption charges over an arms deal dating back more than two decades.