South Africa was in uproar yesterday after prosecutors refused to press corruption charges against the deputy president, Jacob Zuma, over allegations that he received payments from a French company bidding for arms contracts.

The chief public prosecutor, Bulelani Ngcuka, said a special anti-corruption unit had uncovered "prima-facie evidence of corruption", but he had decided not to prosecute because he was not absolutely certain the government would win the case.

The opposition Democratic Alliance said Mr Zuma was "fatally wounded and he should stand down".

But Mr Zuma countered by saying he wanted a chance to clear his name. "The statement is equivalent to a judgment against me," he said. "The purpose ... is to leave a cloud hanging over my integrity."

Mr Zuma is a long-term friend of President Thabo Mbeki and widely regarded as a potential successor.

Investigators had been considering allegations that Mr Zuma discussed receiving payments from the French company Thomson CSF, renamed Thales in 2000, which was bidding for arms contracts. The company denies the allegations.

Mr Ngcuka said he had decided to prosecute South Africa's Nkobi group of companies, which is controlled by Mr Zuma's financial adviser, Schabir Shaik, and Thomson CSF, on charges of contravening company law.

He had handed over evidence to the French authorities.

The French foreign ministry refused to comment on the case, explaining that it was not in its jurisdiction.

With acknowledgements to Andrew Meldrum in Pretoria, Amelia Gentleman in Paris and The Guardian, UK.