The ex-head of the Special Branch of the Malaysian police, Mohamed Said Awang Mohamed Said, told defence laywers that Mr Anwar did not, in fact, abuse his power by persuading police to seek a retraction of sexual misconduct allegations against him.

Facing tough questioning on the fourth day of the proceedings, Mr Said, a key prosecution witness, acknowledged sending a report and letters retracting the allegations to Prime Minister Mahathir Mohammad in 1997.

He also refused to deny that the report implicated senior officials in a plot to oust Mr Anwar from government.

Defence lawyers in the politically sensitive trial are now demanding the "crucial" report be released to the court by the government saying it goes to the "root of the matter".

Mr Anwar faces four corruption charges, which accuse him of using his official position to protect himself from criminal action or proceedings. He faces one further corruption charge and five charges of sodomy.

There has been a strong police presence around the court

Judge Augustine Paul adjourned the proceedings of the trial briefly on Thursday morning after Mr Said, who is set to retire later this month, said the defence had "twisted" his testimony.

To gasps from the public gallery, Mr Said also admitted under questioning that he might be prepared to lie to the court if asked to by someone "higher than the deputy prime minister".

There are 52 potential prosecution witnesses including the prime minister.

'Morally unfit'

The Malaysian prime minister sacked Mr Anwar in early September describing him as "morally unfit".

He said he had talked personally to people who said they had sex with Mr Anwar.

Mr Anwar's sacking and subsequent arrest has provoked widespread demonstrations and political unrest.

Mr Anwar denies charges of corruption and illicit sex and says he is the victim of a political conspiracy.

Few seats have been made available in the public gallery for diplomats and human rights observers, and the United States has led international complaints about the exclusion of official observers.