The findings of an investigation into corruption allegations against South Africa’s President Jacob Zuma are set to be released.
It follows the decision earlier by Mr Zuma to drop a court bid to block the release of the report by former anti-corruption chief Thuli Madonsela.
Mr Zuma is accused of an improper relationship with wealthy businessmen.
Police fired water canon to disperse protesters demanding his resignation in Pretoria.
The protesters, supporters of the EFF (Economic Freedom Fighters) party, had gathered outside Mr Zuma’s main administrative offices.
Opposition groups are also rallying in South Africa’s other major cities.
The president has been dogged by corruption allegations for more than a decade, but has repeatedly denied any wrongdoing.
The High Court in the capital, Pretoria, ordered that the report be released no later than 15:00 GMT on Wednesday.
It came after Mr Zuma’s lawyer informed the court his client would no longer try to block it, but gave no reasons why.
The report is believed to contain damning allegations against Mr Zuma, reports the BBC’s Milton Nkosi from Pretoria.
Ms Madonsela investigated allegations that he let the wealthy Gupta family wield undue influence in his government.
The Guptas were accused of trying to nominate cabinet ministers in exchange for business favours.
Both Mr Zuma and the Gupta family have denied the allegation.
Mr Zuma’s bid to block the report’s release was challenged by opposition parties, which are now demanding that he pays their legal costs.
Thousands of opposition supporters have been rallying in Pretoria, shouting “Zuma must fall”.
Democratic Alliance (DA) leader Musi Maimane said state coffers were being “plundered” by “crooks”, but the “good guys” were winning in the battle to safeguard the democracy which emerged in South Africa at the end of minority rule in 1994.
“This is about letting Zuma, the Guptas and all their useful idiots know that their days are numbered,” Mr Maimane said.