By Alexander Winning
JOHANNESBURG (Reuters) - South Africa's top court ruled on Monday that an anti-corruption official who has accused President Cyril Ramaphosa of serious misconduct had acted in bad faith when investigating an apartheid-era bank bailout.
The strongly worded ruling could undermine the credibility of Public Protector Busisiwe Mkhwebane as she prepares for court cases against her by Ramaphosa and Public Enterprises Minister Pravin Gordhan, a key ally of the president.
"This court upholds the High Court's finding that the public protector acted in bad faith," the constitutional court said.
It confirmed a punitive costs order made against Mkhwebane by the High Court last year for using flawed methods in an investigation she conducted in 2017.
The South African Reserve Bank (SARB) had successfully challenged a recommendation she made in that case that its mandate should be changed as part of remedial actions, and sought that Mkhwebane personally pay some legal costs.
"This court accordingly concludes that the punitive aspect of the cost order against the public protector must stand," the constitutional court said in Monday's ruling.
Mkhwebane's "entire model of investigation was flawed and ... she was not honest about her engagements during the investigation", it added.
Mkhwebane said it was not clear how the public protector's office would be able to do its work "without fear, favor or prejudice" as required by the constitution, given the ruling.
"This will set a precedent for all other public protectors," she said, adding that she would study the judgment before making more detailed comment.
Supporters of Ramaphosa accuse Mkhwebane of acting as a proxy for a faction of the governing African National Congress (ANC) party that is aligned with former president Jacob Zuma, which she denies.
Zuma, who was forced to step down early last year and replaced by Ramaphosa, appointed Mkhwebane for a non-renewable seven-year term in 2016 after the previous public protector, Thuli Madonsela, vacated her post. She can only be removed by parliament.
Mkhwebane has been involved in several acrimonious disputes in recent months.
On Sunday, Ramaphosa said he would urgently challenge Mkhwebane's "flawed" finding in a separate investigation that he "deliberately misled" parliament over a donation in 2017 to his campaign for the ANC leadership.
Mkhwebane, who began the investigation after a complaint from South Africa's opposition, recommended on Friday that Ramaphosa be referred to parliament for violating an executive ethics code over the donation.
The saga is a headache for Ramaphosa, who has staked his reputation on cleaning up deep-rooted corruption and reviving Africa's most developed economy, providing ammunition for enemies including Zuma loyalists within the ANC.
Another of Mkhwebane's recent investigations found that Gordhan had violated the constitution for exceeding his powers while serving as the country's tax commissioner.
Gordhan disputes her findings and has applied to the courts to have them set aside.
Previously South Africa's finance minister, Gordhan in his current role oversees efforts to revive struggling state companies like power firm Eskom and weapons manufacturer Denel.
The main opposition party, the Democratic Alliance (DA), has said Mkhwebane is unfit to hold office and wants parliament to remove her from her post.
The speaker of the lower house of parliament has said she will refer the DA's request to initiate removal proceedings against Mkhwebane to the parliamentary committee on justice and correctional services for consideration.
But it is not clear how the ANC, which has a parliamentary majority, would vote on the issue. Mkhwebane also counts radical leftist party the Economic Freedom Fighters (EFF) among her supporters.
The EFF on Sunday urged Ramaphosa to take a leave of absence while Mkhwebane's investigation into him was reviewed in court.
(Reporting by Alexander Winning; Editing by Catherine Evans)