"The [National Prosecuting Authority] has become an instrument with which the ANC wants to manipulate who will be prosecuted and who will be protected," said Freedom Front Plus (FF Plus) MP Anton Alberts on Wednesday.
Proof of this was the NPA's obsession with taking action against prosecutor Glynnis Breytenbach merely for doing her job, he said.
ANC spokesperson Keith Khoza denied the accusation, saying: "I think people at times make unnecessary comments or they want to draw attention to themselves.
"How does the ANC get involved in the Breytenbach matter? It was an internal matter for the NPA."
On Monday, Breytenbach, a senior NPA prosecutor, was found not guilty on 15 counts by a disciplinary hearing. She was suspended from the NPA on April 30 2012.
At the time, Breytenbach claimed acting National Director of Public Prosecutions Nomgcobo Jiba had suspended her to stop her from prosecuting former police crime intelligence boss Richard Mdluli on fraud and other charges.
The NPA announced on Tuesday it would challenge the hearing's ruling in court.
ANC's political games
Speaking in the National Assembly during debate on the justice department's budget vote, Alberts said the reason the NPA decided to appeal against her acquittal could only be found in the political games the ANC was playing in the department.
"In a world where the Constitution is undermined in this manner, one could rightly ask who could truly feel safe."
Meanwhile, Justice Minister Jeff Radebe defended the NPA's record by saying he was satisfied that the prosecuting body was doing a good job.
Radebe said he was basing his view on the fact that courts were busy and prisons were overcrowded.
"I am satisfied that they are doing a good job," he said, responding to a question from a journalist on Wednesday morning.
"If you look at the number of people that our courts convict on a daily basis, you look at the number of prisoners who are in our courts; there's a complaint that there is overcrowding in our prisons, people don't volunteer to go to prison.
"It's because we have got energetic prosecutors at all levels who prosecute without fear, favour or prejudice. That's why I say I'm satisfied," he said.
Radebe said the few cases cited by the journalist, when the NPA hadn't been successful – Carl Pistorius, Anene Booysen, J Arthur Brown and Breytenbach – were insignificant compared to thousands of cases that the NPA succeeded with in courts. – Sapa