The Democratic Alliance (DA) has filed papers asking the Supreme Court of Appeal to dismiss President Jacob Zuma and the National Prosecuting Authority's (NPA's) requests for leave to appeal a High Court ruling that Zuma's corruption charges be reinstated.

Zuma and the NPA are appealing the North Gauteng High Court's April 2016 ruling that the 783 outstanding charges against him for alleged corruption must be reinstated.

The party on Monday filed its heads of argument, asserting that "both Mr Zuma and the National Prosecuting Authority's requests... are void of any merit and should be dismissed with costs", DA federal executive chairperson James Selfe said.

"We contend that both applications for leave fail to meet the requirements of having a credible chance of success and compelling reasons why they should be heard.

"It is in the interests of the rule of law, due process and the Constitution that the prosecution continue as per the order of the North Gauteng High Court."

Selfe said it was in the "utmost public interest" that Zuma stand trial for the 783 charges of fraud, corruption, racketeering and money laundering without delay.

The appeals will be heard on September 15, 2017. The DA has also asked that they be dismissed with costs.

The party had been fighting for more than eight years for Zuma to "have his day in court", Selfe said.

'What the NPA is doing, I don't know'

In June, DA leader Mmusi Maimane asked Zuma during a question session in Parliament why it had taken the NPA 1 200 days to investigate the charges Maimane had re-laid.

"I think the honourable member is asking the wrong person. You did not lay the charges against me to investigate," Zuma replied.

"What the NPA is doing, I don't know.

"...Why you are asking me, I'm not investigating. You should go to where you made the charges and ask why it is taking long. You are asking the wrong person."

The full bench of the North Gauteng High Court ruled in April 2016 that the decision to discontinue the prosecution against the president should be reviewed and set aside.

The decision to drop the charges, taken by former NPA head Mokotedi Mpshe in 2009, was "irrational", the court said.

The Constitutional Court in October 2016 refused to hear the NPA's appeal on the judgment for the time being, saying it would not be in the interests of justice to hear the matter at that stage.

It needed to go through the Supreme Court of Appeal first.

The DA has previously argued that Zuma and the NPA's appeals have no reasonable chance of success, and that the appeals are a time-wasting tactic.