Mr Anwar's driver, Azizan Abu Bakar, appears to have retracted allegations that he was sodomised by Mr Anwar.

To gasps from the courtroom, Mr Abu Bakar, who worked for Mr Anwar from 1989 to 1992, agreed under intense cross examination with a defence lawyer's statement that "Anwar Ibrahim did not do anything to you".

Defence lawyer Christopher Fernando: "Witness was unreliable"

Before a hushed courtroom, lawyer Christopher Fernando repeated the question: "I put it to you that Anwar Ibrahim did not sodomise you and that is why you visited him between 1992 and 1997. Otherwise you would have kept far away from his house."

Mr Azizan replied simply "Yes".

When asked the question in Malay Mr Azizan gave the same answer, apparently leaving the court in no doubt of what he was saying.

The BBC's Peter Biles: "A serious blow for the prosecution"

Outside the court, Mr Fernando said the dramatic change of testimony had completely discredited Mr Azizan as a key prosecution witness.

But South-east Asia correspondent Simon Ingram says there is confusion about whether Mr Azizan really intended to withdraw the account he had given with some force last week.

Simon Ingram: It's still unclear whether Mr Azizan was withdrawing his statement

Our correspondent says it is possible the driver believed the defence counsel was referring to the years between 1992 to 1997 when he still visited the Anwar family, although he had left their employ.

Mr Azizan has never said acts of sodomy took place after 1992.

Lawyers for the prosecution say they will explain this tomorrow.

'Sex slave'

Mr Anwar maintains his innocence

Mr Azizan had accused his former employer of sodomy in a letter that was sent to Prime Minister Mahathir Mohamad in 1997.

His allegations are crucial to the prosecutions case against Mr Anwar.

In testimony last week, he told the court that shame and guilt kept him from making Mr Anwar's repeated homosexual acts public. He said the former deputy prime minister had turned him into a "homosexual slave".

But during cross-examination, Mr Azizan wavered on his testimony, prompting defence accusations that his story was inconsistent and contradictory.

Mr Anwar was arrested in September and charged with corruption and sexual offences shortly after being fired from the government by Dr Mahathir.