The National Prosecuting Authority (NPA) says it will "resist" further delays in the long-awaited corruption trial of Jacob Zuma and French arms company Thales – and stressed that "despite any appeals, the matter must proceed".

The NPA expressed this a day after Judge Piet Koen in the KwaZulu-Natal High Court in Pietermaritzburg dismissed all six applications Zuma launched to challenge the legitimacy of his corruption prosecution – and ordered that the case against him and Thales should proceed on 11 April 2022.

In a 61-page ruling, Koen reiterated what the NPA previously argued, that Zuma did not have the legal right to appeal the dismissal of his "special plea" challenge to State advocate Billy Downer's title to prosecute him now. After citing multiple court rulings, Koen said it was clear that such an appeal could happen only if and when Zuma was convicted of the arms deal corruption he is accused of.

"On the peculiar facts relating to this matter," Koen said, "an appeal against the dismissal of the special plea, if successful, would not lead to a 'just and prompt resolution of the real issues between the parties' before this court, in this instance Mr Zuma's guilt or innocence."

"In the absence of a prompt resolution of that real issue between the parties, there is no scope for an appeal prior to conviction, based on S 17(1)(c) of the Superior Courts Act."

He added that, even if it was heard at this stage, Zuma's appeal had "no prospects of success".

In a statement released on Thursday morning, the NPA said it "noted" Koen's ruling that the "interests of justice require that the matter now proceeds to trial in respect of the not guilty pleas of the two accused (Zuma and French arms company Thales) – and his order that the case against the two proceed on 11 April.

"The NPA will be fully prepared to proceed on 11 April 2022, and it will do all that it can to ensure that the trial continues, despite whatever further steps there may be to delay the trial by yet further applications to appeal," said NPA spokesperson Mthunzi Mhaga.

The NPA has typically put trials on hold to allow for the hearing of legal challenges to prosecutions and subsequent appeals – so its decision to push for the case against Zuma to go ahead regardless of any appeal he may lodge, could set an important future precedent.

"No appeal should be an impediment to the resumption of trial, given that the appeal itself should have been lodged after the conclusion of the trial. Hence, the prosecutors will be opposing any postponement of the trial when it resumes on 11 April," Mhaga said.

"We are on solid legal ground here."

Zuma stands accused of corruption in relation to allegations that he was kept on a corrupt retainer by his former financial advisor, Schabir Shaik, in exchange for his using his position to further Shaik's business interests.

It is the State's case that Zuma also accepted a R500 000-a-year-bribe – facilitated by Shaik – to protect Thales from any potential investigation into South Africa's multibillion rand arms deal.