JOHANNESBURG (Reuters) - Three cabinet ministers removed by President Jacob Zuma in a reshuffle last week quit as lawmakers of his African National Congress on Thursday ahead of a vote of no-confidence in him that the ANC has said it will defeat.
Mcebisi Jonas, an outspoken critic of government corruption who was deputy finance minister until Zuma sacked him, resigned as a member of parliament along with Tina Joemat-Pettersson and Dipuo Peters, axed as energy and transport ministers last week.
They will be replaced with candidates from an ANC list.
The ANC has rejected calls from opponents and some long-time political allies for Zuma to resign after the reshuffle, centred on the sacking of Pravin Gordhan as finance minister, cost the country one of its investment-grade credit ratings.
South Africa's rand ZAR=D3 has tumbled more than 11 percent since March 27 when Zuma ordered Gordhan home from overseas meetings with investors.
It was not clear if Gordhan would also step down as an MP.
"I am resting now. I will see you on the 18th," he said when asked on Thursday. Parliament will vote on the no confidence motion against Zuma on April 18.
Jonas made headlines last year when he said he had been offered the finance minister's job by members of the Gupta family, Indian businessmen who have close ties with Zuma and have been accused of influence-peddling. Zuma and the Gupta family have denied any wrongdoing.
The main opposition Democratic Alliance (DA) party encouraged Jonas to challenge Zuma, who has denied repeated allegations of corruption since winning power in 2009.
"We can only hope the former deputy minister will have the courage and energy to fight on against 'state capture'," its shadow finance minister David Maynier said, referring to accusations against the Guptas which they have rejected.
Zuma, 74, has survived four previous no confidence votes. The ANC has a commanding majority in the national assembly and said on Thursday that its members would vote against the motion.
The ANC Chief Whip's office rejected calls for a secret ballot for the no-confidence motion. The opposition has said this could make it possible for ANC lawmakers to vote against Zuma without facing reprisals.
In another blow to Zuma, the Treasury said its Director General Lungisa Fuzile, who is well respected in financial markets and worked closely with Gordhan and Jonas, would leave after new Finance Minister Malusi Gigaba takes the reins.
Gigaba has declared plans to redistribute wealth in the economy to poor black people as part of a programme of "radical socio-economic transformation" promised by Zuma..
Inequality still festers in South Africa more than 20 years after the end of white-minority rule.
Fears that budget discipline could falter under Gigaba have contributed to market jitters, but he and Zuma have assured investors they will maintain policies established under Gordhan.
Zuma has pledged to expropriate land but analysts said violent seizures of farms like those in neighbouring Zimbabwe were unlikely.
Fitch Ratings is likely to follow S&P by downgrading South Africa's credit rating to "junk", analysts said, which would further push up the country's borrowing costs.
S&P cited the sacking of Gordhan, a two-time finance minister regarded as a steady hand by the international investors on whom South Africa relies to finance its hefty budget and current account deficits, to explain the rating cut.
"We didn't need the downgrade, by the way, if we had just behaved ourselves," Gordhan said on Thursday at a memorial in Cape Town for veteran anti-apartheid stalwart Ahmed Kathrada.
Thursday's resignations are an embarrassment rather than a direct threat to Zuma. But he still faces demands to step down from political and civil society groups that will march on Friday in protest against the president, who they say will hurt the economy and cost yet more jobs by staying in office.
Zuma welcomed civil society group SaveSA's plans to protest outside his office, saying it was their legal right to do so.
The DA will march in the commercial hub Johannesburg.
The South African Communist Party, a historic ally of the ANC which has also demanded that Zuma step down, said it had postponed its planned march in Pretoria to a later date. A "holding hands" picket is planned in Cape Town.
"The marches in themselves will not have an effect on the ANC, the only thing that will have an effect will be the internal ebb and flow of its factions," said political analyst Daniel Silke.
Additional reporting by Olivia Kumwenda-Mtambo, Mfuneko Toyana and TJ Styrdom in Johannesburg and Wendell Roelf in Cape Town; Writing by James Macharia; Editing by Catherine Evans