Zuma is seen as a likely successor to Mbeki

Jacob Zuma had been accused in the media of having discussed receiving payments from a foreign company bidding for arms contracts.

"Whilst there is a prima facie case of corruption against the deputy president... we are not sure if we have a winnable case," Prosecutor Bulelani Ngcuka said on Saturday.

Mr Zuma - who is widely seen as a likely successor to President Thabo Mbeki - has repeatedly denied the allegations.

The sooner the matter is concluded the better Thabo Mbeki South African president

The body which Mr Ngcuka heads, the National Directorate of Public Prosecutions (NDDP), had used its elite investigating unit, the Scorpions, to examine the allegations against Mr Zuma.

In July, South African President Thabo Mbeki called for the investigation against his deputy to be conducted as quickly as possible.

"You can't have it dragging on forever. The sooner the matter is concluded the better," he said.

Well-known figure

Mr Zuma is one of several high-profile members of the ruling African National Congress who have become embroiled in corruption scandals.

Earlier this year, former ANC chief whip Tony Yengeni was sentenced to four years in prison after receiving a discounted luxury car while he negotiated a multi-billion dollar arms deal with companies in Europe and misleading parliament when questioned about the incident.

The case was seen as an important test of the government's commitment to stamping out corruption but the scandal and the accusations surrounding Mr Zuma have dented the image of the ANC party.

Mr Zuma, 61, has a high profile in Africa as a leading negotiator on peace deals in Burundi and the Democratic Republic of Congo.