Cape Town — Seven years after taking office, President Jacob Zuma again faces a court battle over corruption charges first investigated while Thabo Mbeki was president.

A South African court ruled on Friday that a decision to drop 783 corruption charges against Zuma just months before he took office  was "irrational". However, the ruling is likely to be taken on appeal to higher courts. Zuma's term of office ends in 2019.

Justice Aubrey Ledwaba, the Deputy Judge President of the Gauteng High Court in Pretoria, said that the acting head of the National Prosecuting Authority (NPA), Mokotedi Mpshe, had acted under pressure in dropping the charges in 2009.

Mpshe had "ignored the importance of the oath of office which demanded that he act independently and without fear or favour," the judge said. "Mr Zuma should face the charges outlined in the indictment."

Mpshe stopped the prosecution on the grounds that there was political meddling in the timing of bringing charges.

Zuma was fired by Mbeki as deputy president of the country in 2005 after his former financial adviser had been convicted on fraud and corruption charges. However, Zuma mounted a vigorous campaign in the ruling African National Congress, in which he dislodged Mbeki as party leader in 2007.

In court on Friday, the opposition party which had brought the application for corruption charges to be reinstated, the Democratic Alliance, responded to the ruling by announcing that it would return to the NPA to demand that Zuma be prosecuted.

"We want Jacob Zuma to have his day in court," the party leader, Mmusi Maimane, told the SA Broadcasting Corporation. If the African National Congress appealed today's decision to the Supreme Court of Appeal or the Constitutional Court, "we will fight them... because it's time now that Jacob Zuma faces the full might of the law."

Zuma's office said he "will give consideration to the judgement and its consequences and the remedies available in terms of our law."