Mr Anwar, who is accused of corruption and sexual offences, says he was assaulted during his detention - a charge which has attracted mounting international concern.

The bruising on Anwar's face has sparked international condemnation

A police officer has been appointed to look into the allegations by Mr Anwar, who was arrested after an increasingly bitter dispute with the prime minister, Mahathir Mohammed, about the need for economic reform.

Mr Anwar is due to appear in court again on Monday, when his lawyers say he will deny all charges.

The investigation follows the release of a medical report on the injuries sustained by Mr Anwar.

Wan Azizah says the police are harassing her

The report said bruising on Mr Anwar's face was apparently caused by an assault, and not - as suggested by the Malaysian prime minister, Dr Mahathir Mohamad - self-inflicted.

Mr Anwar's wife, Wan Azizah Ismail has accused the authorities of "harassment and persecution" after she was summoned for a third time for police questioning on Thursday.

Sedition charges

Correspondents in Kuala Lumpur say the authorities there are keen to dissuade Wan Azizah from taking over the leadership of Malaysia's fledgling opposition movement from her husband.

Wan Azizah faces possible charges of sedition after expressing fears in a television interview with CNBC Asia that her husband may be injected with the HIV virus to 'prove' charges of illegal homosexual conduct.

Her lawyer, Sivarasa Rasiah, said police had also interviewed him. "The lawyers shouldn't be subjected to this," he said, "least when they are performing their legal duties or servicing their clients.

"I think the Bar Council will have something to say about this."

International concern grows

James Wolfensohn: Anwar a close friend

Meanwhile the President of the World Bank, James Wolfensohn, who is a close friend of Mr Anwar expressed his "deep concern" at the former deputy premier's condition.

Mr Wolfensohn said it was important for the international community to continue to monitor the situation.

His comments echo those of a growing number governments and international organisations following Mr Anwar's appearance in court on Tuesday with a black eye and other bruising which he said was the result of a police beating.

James Wolfensohn, World Bank president: "As a friend of mine, of course I'm worried about him"

US Treasury Secretary Robert Rubin added to concerns already expressed by US Government.

He said Mr Anwar was "a highly respected member of the international financial community" and described him as "a great force for great good in many ways."

Mr Anwar's treatment in prison was, said Mr Rubin, "deeply, deeply troubling."

In another development, one of Mr Anwar's supporters, Ahmed Zahid Hamidi, has resigned from a key post in Malaysia's governing UMNO party - a move seen as possible evidence of a growing rift within the party.