Former judge Willem Heath has called for criminal charges to be brought against President Thabo Mbeki, former justice minister Penuell Maduna and former chief prosecutor Bulelani Ngcuka.

Heath told the weekly Mail & Guardian newspaper that last week's findings by Judge Chris Nicholson were tantamount to prima facie evidence of contraventions of the National Prosecuting Authority (NPA) Act by Mbeki, Maduna and Ngcuka.

Nicholson found that the decision to prosecute ruling party leader Jacob Zuma on fraud and corruption charges was invalid.

Heath said South Africans should be protected against the "systematic abuse, detailed in the judgment, of organs of state by the president and his purported henchmen".

"If the behaviour found by Nicholson is not addressed, the application of the principle of the separation of powers will remain at the whim of those who have seemingly been using it most effectively for personal gain," said Heath.

He criticised the NPA's decision to appeal against Nicholson's ruling.

"The findings of Judge Chris Nicholson... will profoundly impact on South Africa. It is probably the most important judgment delivered in this country in the past many years.

"What is macabre is that the NPA has decided to lodge their intent to appeal the judgment.

"The NPA, represented by Billy Downer SC and Wim Trengove SC in their battle against Zuma, has been given a long overdue chastising for their maverick behaviour -- behaviour which is not limited to the Zuma case," said Heath.

He said it was "astounding" that the two senior counsel "did not recognise the procedural irregularities perpetrated by the three consecutive [national directors of public prosecutions] and allowed themselves to be led by such irregularities."

Meanwhile, the suspended national director of public prosecutions, Vusi Pikoli, told the SABC that the decision to prosecute Zuma was based purely on legal grounds and not political grounds, as was hinted by Nicholson in his judgment.

Pikoli, who has been suspended by Mbeki for an alleged breakdown in his relationship with Justice Minister Brigitte Mabandla, denied that he was ever influenced in deciding to prosecute Zuma.

Pikoli said the decision by the NPA to appeal Nicholson's decision should be respected.