Zuma's battle against the charges is likely to decide whether the African National Congress leader takes over from President Thabo Mbeki next year, when he has to step down.

Nine of the 10 judges on the Constitutional Court said warrants used in raids on Zuma and his lawyer were valid and the state could use seized documents in its prosecution.

In another blow to Zuma, the court cleared the way for the use of a diary and other documents from Mauritius in the trial. Zuma had tried to block the National Prosecuting Authority (NPA) from obtaining the documents.

"We are certainly very pleased with the outcome today," NPA spokesman Tlali Tlali said after the ruling by the court in Johannesburg. "The NPA is court ready."

Zuma is accused of accepting hundreds of thousands of dollars in bribes from a French arms firm. He denies the charges and is expected to go on trial this year for corruption, money-laundering, fraud and racketeering.

His supporters have repeatedly branded the case against Zuma a conspiracy by loyalists of Mbeki. They say state organs were used to smear Zuma and derail his political ambitions.

The ANC said it respected the Constitutional Court ruling but remained disturbed by aspects of the investigation.

"The ANC reiterates its view that the manner in which this case has been handled by the authorities over the last few years has reinforced the perception that the ANC President is being persecuted rather than merely prosecuted," it said.

"It has also fuelled doubts about his chances of receiving a fair hearing."

ZUMA SAYS RIGHTS VIOLATED

Mbeki fired Zuma as deputy president in 2005 after the arms scandal broke, and Zuma was later charged with bribery and fraud. His corruption case collapsed in 2006 on procedural matters, but prosecutors charged him again in 2007.

A protracted trial could mean Zuma's case eventually overlaps with general elections in 2009, potentially causing further political instability in Africa's largest economy.

Investors are concerned that Zuma could bring a shift to the left in South Africa after Mbeki's business friendly policies.

Prominent trade unionists, Communists and rank-and-file ANC members are expected to be at Zuma's side when he goes to court in Pietermaritzburg next week to ask for the entire case to be dismissed.

While publicly stating that he wants to go to trial, Zuma has fought hard to kill the case before it reaches a courtroom.

Zuma and his lawyer Michael Hulley have argued that an elite crimefighting unit violated their rights when they raided their properties in 2005. They said the search warrants used were illegal and violated their privacy, property and other rights.

The Supreme Court, however, previously ruled that the documents seized by the FBI-style Scorpions unit could be used against Zuma when he went to trial, despite finding some problems with the warrants.

That ruling was upheld by the Constitutional Court on Thursday.