Cape Town (AFP) - Named this year by Time magazine as one of the world's 100 most influential people, South Africa's Public Protector Thuli Madonsela would probably top the government's list of the most irritating.

The softly-spoken 51-year-old mother of two has shown a steely resistance to political pressure in her role as government-appointed ombudswoman, clashing head-on with President Jacob Zuma.

In any country in the world her determination to hold the highest office to account would be admirable. In South Africa and many other countries on the continent it is revolutionary.

Madonsela has become the figurehead for a wave of outrage over the spending of $24 million (18 million euros) of taxpayers' money on so-called "security upgrades" at Zuma's private rural residence at Nkandla in the southeastern KwaZulu-Natal province.

It is just one of her many interventions against the abuse of power and the public purse since her appointment to the constitutional post in 2009, but it has caught the popular imagination and led to an unprecedented revolt in parliament this month.

Zuma, 72, was questioned in the assembly over his response to Madonsela's report on Nkandla, which found that he had benefitted improperly from the upgrades and should refund some of the costs.

When he hedged his answers, the session collapsed in chaos, with a group of radical lawmakers jumping to their feet, banging tables, pointing fingers at him and yelling repeatedly: "Pay back the money".

Many criticised the rowdy disruption of parliament, but it was clear through both mainstream and social media that the sentiment was widely shared and that Madonsela had faced down government efforts to intimidate or ignore her.

Not bad for a woman who grew up in a working class family in the segregated black township of Soweto near Johannesburg under the repressive racial policies of apartheid.

- Humble origins -

Madonsela rose from those humble beginnings to become a constitutional lawyer, working as a technical adviser for the drafting of South Africa's democratic constitution after the end of apartheid in 1994.

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That constitution was adopted by the government of late African National Congress (ANC) leader Nelson Mandela and included the role of public protector as a guardian against abuse of power and corruption.

The ANC under Zuma has been increasingly criticised for abandoning the principles that guided Mandela, and the party has rounded on Madonsela over her persistence on the Nkandla scandal.

On Thursday, she called a news conference and in typically calm and collected style outlined her role and announced that far from dropping the issue she has asked for a face-to-face meeting with Zuma.

"Thuli Madonsela is an inspirational example of what African public officers need to be," Nigeria's former central bank governor Lamido Sanusi wrote in Time magazine's commendation.

"With her ability to speak truth to power and to address corruption in high places, Madonsela has been outstanding."

Despite being academically gifted, her life was not all smooth sailing.

In a "Letter to my 16-year-old self" -- part of a series in Oprah Winfrey's O Magazine in 2012 -- she wrote: "I know you are socially awkward, plagued by a nagging feeling of being unloved and ugly.

"Perhaps this comes from being teased about your big head and, more recently, two of your academically inferior classmates have started taunting you, too. Having two sisters whose beauty is always noticed and praised has not helped either."

But, with the perspective of a 50-year-old, she goes on to say: "Your fears of being unlovable were unfounded. You have been loved and supported beyond measure throughout your life."

Never more so, surely, than now, when she has widespread support and admiration throughout South Africa.