DA leader Helen Zille has been barred from entering the National Prosecuting Authority (NPA) offices on Monday where an announcement on the prosecution of ANC leader Jacob Zuma will be made.
"By barring me here today, they are showing that they are not abiding by their policy. A press conference is an open thing. There should be no bar on the public coming to listen. I need to hear first-hand and not rely on second-hand sources," Zille told reporters.
If the NPA would not allow her to ask questions at the press conference, she would go to a court of law to get answers, said Zille.
"We want the full reasons ... If we see the charges against Jacob Zuma withdrawn, then we have selective prosecution."
If the NPA intended to continue with investigations into other players in the saga, that would also amount to selective prosecution, she said.
"If other people are guilty, they must be charged. If Jacob Zuma is guilty, he must be charged. We are not going to let this lie."
Zille described the current situation as a "constitutional crisis".
"We are going to stand up and protect this Constitution. We all need to stand up and stop this power abuse and rape of justice.
"If that ceases to be the case then the rule of law is at peril," said Zille.
Zille said she would not force her way onto the premises. However, she would not abandon her post outside its main gate either.
About 40 members of the Congress of the People together with some ID supporters protested in the street outside the building in Pretoria.
Some held placards stating: "NPA - what are you hiding?
Cope's Gauteng youth secretary, Ngcini Tshwaku, said the party would ask for a national meeting with all political parties if charges against Zuma were dropped.
"The NPA must not bow to political pressure and they must focus on the ball," said Tshwaku.
Acting NPA head Mokotedi Mpshe is scheduled to hold a press conference at 10.30am after weeks of speculation, reported to be driven in part by Zuma's allies, that he would scrap the corruption prosecution of the ANC leader eight years into the case and two weeks before the elections. - Sapa