Shaik always protested his innocence

Schabir Shaik was found guilty last week on two counts of corruption and one of fraud but remains free on bail.

Analysts say the verdict raises the possibility of criminal charges against Mr Zuma, who was seen as a favourite to succeed President Thabo Mbeki.

Meanwhile, 21 politicians have appeared in court on charges of fraud.

The current and former MPs, mostly from the governing African National Congress (ANC) are accused of misusing official travel vouchers in an alleged fraud, using $3m (�1.6m) of taxpayers' money.

Struggle subverted

The Shaik sentencing was broadcast live on national television.

The BBC's Barnaby Phillips in Johannesburg says Shaik appeared shocked as the judge delivered the sentence.

Jacob Zuma has said his conscience is clear

He is set to appeal.

Judge Hilary Squires jailed Shaik for 15 years on two counts and three years on a third count, the sentences to run concurrently, AFP reports.

Judge Squires compared corruption to a cancer subverting democracy and human rights and rejected the defence lawyer's plea for clemency because Shaik had fought apartheid.

"His corporate empire's progress and prosperity was plainly linked to the possibility that Jacob Zuma would finally ascend to the highest political office," he said.

"Far from carrying out the object of [South Africa's liberation] struggle, this whole saga represents a subversion of it."

"It was a typical example of a privileged treatment to a selected political figure in a situation redolent with lack of transparency and subversive of administrative fairness and integrity. And that is what the law seeks to punish."

Dancing MPs

As the sentence was being handed down, Mr Zuma was making his first public appearance since last Thursday's guilty verdict, in parliament.

ANC MPs danced and sang his name, while opposition lawmakers called for him to resign.

They were, however, not given the opportunity to question him directly about the corruption verdict.

Our correspondent says Mr Zuma looked relaxed and composed.

After the verdict, Mr Zuma said his conscience was clear.

The case has its roots in an investigation into corrupt practices surrounding a R6bn ($1bn) arms procurement deal by the South African government.

During the course of that investigation, in 2003, Mr Zuma denied that he had attempted to secure a bribe from the French arms company Thales, which has since become Thomson CSF.