South African state prosecutors will Monday respond to a court ruling that President Jacob Zuma should face almost 800 corruption charges, in a move that could threaten his hold on power.

The charges, relating to a multi-billion dollar arms deal, were dropped in 2009, clearing the way for Zuma to be elected president just weeks later.

The prosecutor justified dropping the charges by saying that tapped phone calls between officials in then-president Thabo Mbeki's administration showed political interference in the case.

But a court last month dismissed the decision to discontinue the charges as "irrational" and said it should be reviewed.

Zuma has endured months of criticism and growing calls for him to step down after a series of corruption scandals amid falling economic growth and record unemployment.

Pressure on the president would increase if some or all of the 783 charges -- which relate to alleged corruption, racketeering, fraud and money laundering -- were reinstated.

"Zuma might remain in office while any prosecution was going on, which would undermine his role as president," Shadrack Gutto, professor for African Renaissance Studies at the University of South Africa (Unisa), told AFP.

"Any charges would add pressure for him to step aside."

The ruling African National Congress (ANC) party faces tricky local elections in August, but Zuma retains widespread support within the party and has appointed many loyalists to key positions countrywide.

Last month, a commission that Zuma set up cleared all government officials -- including himself -- of corruption over the 1999 arms deal.

He was accused of having accepted bribes from international arms manufacturers.

The tapped phone recordings, which became known as the "spy tapes", were kept secret until they were released in 2014 after a long legal battle fought by the main opposition party, the Democratic Alliance (DA).

The DA hopes to make major gains in the August elections, tapping into discontent over the ANC's struggle to deliver jobs, houses and education 22 years since the end of apartheid rule. 

In March, the president lost another major legal case when the country's highest court found he violated the constitution over the use of public funds to upgrade his private residence.

The so-called "security" work, which cost taxpayers $24 million, included a swimming pool, chicken run, cattle enclosure and an amphitheatre.

Zuma, 74, will have completed two terms in 2019 and is not eligible to run for president again, but the ANC could replace him ahead of the next general election.

The National Prosecuting Authority (NPA) had until Monday to announce its decision after the Pretoria High Court ruling last month.

A NPA spokesman said a press conference would be held at 10:00 am (0800 GMT).

Source: AFP