Johannesburg - Public Protector Busisiwe Mkhwebane wants President Jacob Zuma to comply with an order by her predecessor and appoint a judge to investigate influence-peddling allegations in government, court filings showed on Thursday.
Then Public Protector Thuli Madonsela, a constitutionally mandated watchdog, said in a report in November that a full investigation was needed into allegations that members of the Gupta family, friends of Zuma, wielded undue influence over political appointments and the awarding of government tenders.
The Gupta family and Zuma deny wrongdoing.
Madonsela, who left office the day after her report was released, called for a full judicial inquiry. Zuma has challenged the need to open that probe.
Mkhwebane, Madonsela's successor, has filed papers with the high court saying Zuma should have complied with her predecessor's report by December and opened a judicial inquiry, the court papers showed.
Zuma's spokesperson did not respond to a request for a comment.
Persistent corruption allegations are piling pressure on Zuma and there are increasing calls from within the ANC for him to stand down. Parliament will hold a no-confidence vote on Zuma next month.
South African media have been dominated in recent weeks by stories - based on more than 100 000 leaked Gupta company emails and documents - about how Gupta-controlled firms do business with state-run and international firms.
Big global names are being drawn into the scandal.
German technology company, SAP, told Reuters on Wednesday it had placed four senior managers in South Africa on leave and opened an investigation after it was accused of taking kickbacks from a Gupta-owned company.
SAP has denied any wrongdoing.
London-based public relations firm Bell Pottinger apologised last week and said it had fired a partner in charge of a South African PR campaign for a Gupta-owned company that the political opposition said inflamed racial tensions.