JOHANNESBURG (Reuters) - The judge leading an inquiry into claims of influence-peddling against former South African president Jacob Zuma on Monday urged more witnesses to come forward, as public hearings began in a case that could last two years.

Former South African President Jacob Zuma reacts after his court appearance in Pietermaritzburg, South Africa, July 27, 2018. REUTERS/Rogan Ward

Deputy Chief Justice Raymond Zondo will review allegations that the Gupta brothers - who headed one of the country’s largest conglomerates - unduly influenced Zuma over political appointments and winning government contracts.

The allegations and other scandals surrounding Zuma’s nine-year rule forced him out of office in February.

Cyril Ramaphosa, who succeeded him as president, has promised to crack down on graft and revive a stagnating economy that lost momentum and suffered credit downgrades during Zuma’s tenure.

It was unclear on Monday whether Zuma or the Guptas - who all deny any wrongdoing - will appear at the inquiry, which is empowered to make recommendations for prosecutions.

Zondo said at the start of hearings that a call for members of the public to come forward with evidence of influence-peddling had so far borne little fruit.

“The response has been quite disappointing. I would like to take this opportunity once again to ask the public to come forward with any information. If this commission is to do its job properly we need evidence,” he said.

A political analyst said people were still afraid to give evidence, partly because they feared for their careers, noting the ruling African National Congress remained faction-riven following Ramaphosa’s appointment.

“Whistleblowers are still watching nervously to see how the political winds will blow,” said Daryl Glaser, a political studies professor at the University of the Witwatersrand.

Zondo said in May that his inquiry could last two years.

It stems from a 2016 report into alleged influence-peddling by the Public Protector, South Africa’s main anti-graft authority.

That report, which stopped short of asserting crimes had been committed, called for an investigation into whether Zuma, some of his cabinet members and some state companies acted improperly.

Among the cases it reviewed was an allegation by Deputy Finance Minister Mcebisi Jonas that the Guptas offered to secure him his boss’s job, as well as claims that Zuma directed state firms to award tenders to the Guptas.

Zuma says the three Gupta brothers - Atul, Ajay and Rajesh - are his friends but he denies any influence-peddling in their relationship.

The exact whereabouts of the Guptas are not known. The brothers, officials from their companies and their family representatives could not be reached for comment on Monday.

South African judicial authorities have declared Ajay Gupta a “fugitive from justice”. He is known to have left South Africa for Dubai in February.

In a separate criminal case, Zuma faces 16 charges of fraud, racketeering and money laundering relating to a deal to buy European military hardware to upgrade South Africa’s armed forces in 1994. His denies the charges.

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