Public Protector Busi Mkhwebane's recommendation to alter the South African Reserve Bank's principal constitutional mandate of maintaining currency and price stability to focus on economic growth has highlighted worsening divisions between the country's state institutions.

Both the central bank and parliament plan to mount legal challenges to the proposal.

Mkhwebane defended her recommendation but said she was willing to hold discussions with those opposing it, news agency Eyewitness News (EWN) reported.

"I haven't overstepped and I think those will be the deliberations which we'll be having further and again. I'll see how the notice of motion, the content and why are they disputing that. We'll take it from there," Mkhwebane was quoted as saying.

Mkhwebane made her proposal on Monday as she delivered her findings on an apartheid-era bailout of Barclays Africa Group. The lender has denied any wrongdoing.

Her call threatens to further stain South Africa's image as an investor-friendly emerging market, coming less than a week after mines minister Mosebenzi spooked investors by raising the minimum threshold for black ownership of mining companies to 30 percent from 26 percent.

The row over the central bank's role has also highlighted divisions in the tripartite political alliance of the ruling African National Congress party (ANC), the country's biggest union, Cosatu, and the South African Communist Party (SACP).

Both the ANC and the SACP are opposed to altering the role of the central bank while Cosatu has backed calls for changes.

(Reporting by Olivia Kumwenda-Mtambo; Editing by Helen Popper)