South Africa's newly appointed second Public Protector, African National Congress MP Lawrence Mushwana, says he will show his critics what he is made of.

Under fire from the Democratic Alliance for being politically biased because he is a public representative of the ANC, Mushwana says: "What I like about what the DA are saying is that it sharpens the challenge to me to prove them wrong."

Mushwana is to resign from the ANC, a move he describes as "non-negotiable".

Despite his long history in the liberation movement - he first became active in the underground in 1973 - Mushwana says he won't be fazed if his term of office includes numerous complaints from the DA about his former political bosses.

"To me a complaint from the DA wouldn't be a complaint from an opposition. It's a complaint about something that has not gone right . . . I would not like to be someone who is known to condone corruption," he says.

As a presiding officer in Parliament - he is deputy chairman of the National Council of Provinces - Mushwana asserts he is proud that he has proved his objectivity time and again.

He has frequently made rulings against the ANC and most recently had an ANC member removed from the House after she ignored his warnings to desist from being "unruly".

But the DA has greeted his appointment by Parliament on Friday with cynicism.

The party said it was an attempt by the ANC to transform "independent institutions into organs of the (ANC) National Executive Committee to hold onto their power".

According to DA spokesman Hendrik Schmidt, the ANC-dominated committee that chose Mushwana had not seriously considered any of the other candidates. But Mushwana is not keeping quiet about what he believes are unfair allegations.

"They are saying that the Public Protector should be apolitical. That's an ideal situation - but it's not a real one."

He also believes that the DA has been less than honest in slamming his appointment. "Before they even interviewed me, they had already dismissed me."

Mushwana says that he is ready to build on the successes of his predecessor, Selby Baqwa.

Mushwana, an attorney, was a rural boy who grew up herding cattle in the Limpopo province. A sign of his deep rural roots is that Mushwana has no accurate record of his birth date, which his parents estimated to be around 1948.

With acknowledgements to Carol Paton and Sunday Times.