Jacob Zuma, the controversial leader of South Africa’s ruling African National Congress (ANC), yesterday received a huge boost in his attempt to become the country’s next president, when a High Court Judge threw out corruption and fraud charges against him.

Judge Chris Nicholson told a court in Pietermaritzburg that the decision to charge Mr Zuma, 66, in relation to a multimillion-pound arms scandal was “invalid and set aside”.

In a two-hour indictment of state prosecutors and the Government of President Mbeki, Mr Zuma’s bitter rival, the judge effectively accepted that Mr Zuma had been the victim of a political conspiracy. He lamented what he called “baleful political influence” and said to cheers and ululations: “I believe the national directorate of public prosecutions ought to have heard the applicant’s representation.”

The ruling triggered scenes of joy from scores of Zuma supporters and top ANC figures inside the court and wild partying by thousands of demonstrators outside. It could signal months more political uncertainty, with some ANC figures certain to call for the President to step down from office early or even face impeachment.

Mathews Phosa, ANC treasurer and a senior party figure, told The Times: “We are delighted! This is a vindication of everything we have argued for the last seven years. There has been massive abuse of power by the Government and Mbeki. The ANC will have to study this ruling before deciding how to act.”

Mr Zuma will be the ANC’s presidential candidate in elections due in April next year when Mr Mbeki steps down after two terms in office. It is an election that the ANC is certain to win. Mr Zuma, a hugely popular grass-roots politician and the country’s most famous polygamist with at least four wives, has battled corruption charges for years. In 2005, his former financial adviser was found guilty of accepting bribes on his behalf and he was himself charged a few weeks later, though that case collapsed on a technicality.

He was then recharged on 16 counts of fraud, corruption and racketeering relating to a 2001 deal in which the French arms manufacturer Thint is accused of paying backhanders to obtain contracts. His supporters maintain that he was a victim of a political conspiracy by pro-Mbeki aides, many of whom have not faced prosecution despite allegations of deeper involvement in the affair.

Mr Mbeki, 66, dismissed Mr Zuma as the country’s deputy president in 2005, but the charismatic Mr Zuma took the battle to the heart of the ANC and last December ousted his rival as party president.

The dispute between the two men has triggered the biggest political crisis in South Africa since the end of apartheid in 1994 and has scared investors.

Two years ago Mr Zuma, the darling of the black township masses, was acquitted in a separate rape case that severely damaged his credibility after he admitted having unprotected sex with an HIV-positive family friend half his age. He then said that he took a shower to avoid contracting the virus, appalling activists in a country with the world’s highest number of HIV/Aids sufferers.

Judge Nicholson emphasised that the decision to throw out the case was not a reflection of Mr Zuma’s guilt or innocence.

However, the National Prosecuting Authority will come under huge pressure not to file charges again. Parliament is pushing through legislation to scrap its elite investigating unit, the Scorpions, in response to ANC anger over what its members see as the persecution of Mr Zuma.

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