Simon Ingram reports from Kuala Lumpur

They say Mr Anwar has disappeared following his arrest at the weekend.

Wan Azizah Ismail: "Apparently I have incited distrust in the criminal judiciary system"

Malaysian police have sealed off Mr Anwar's home and are questioning his wife, Wan Azizah Ismail, on charges of possible sedition.

The police action follows an interview in which Wan Azizah said she feared the police might inject her husband with the HIV virus in order to prove allegations of sexual misconduct.

The Malaysian Prime Minister, Dr Mahathir Mohamad, dismissed her allegations. "We never did this before, so why would we do it now?" he said.

The BBC Correspondent in Kuala Lumpur, Simon Ingram, says the Malaysian government is plainly determined to throttle the nascent campaign calling for political reform Mr Anwar was spearheading in the weeks prior to his detention.

Unlimited detention

Mr Anwar is expected to be charged with sexual misconduct

Mr Anwar was arrested on Sunday and is currently being held under the terms of Malaysia's Internal Security Act (ISA), which provides for indefinite detention without trial.

Since his arrest, Malaysian police have used tear gas and water cannons to disperse protests by thousands of Mr Anwar's supporters. Several have been arrested.

Wan Azizah says she has not been allowed to see her husband since he was taken into custody.

David Willis reports from Malaysia

On Tuesday Dr Mahathir said that his former deputy had incited public unrest with the intention of destabilising the country.

"It is clear that he was working up emotion in order to develop the kind of situation that was found in Indonesia," he said.

'Vile' allegations

Dr Mahathir: 'You have to be a little rough'

"He wants to be arrested under the ISA so that he can accuse the government of being oppressive," he said.

Mr Anwar has accused the prime minister of conducting a smear campaign against him with accusations of adultery and homosexuality.

But the prime minister says he has personally interviewed people who admitted engaging in illegal sex acts with Mr Anwar and because the allegations were so vile he decided to question people himself.

Sulaiman Abdullaa, Mr Anwar's lawyer: "So far we've not seen any case"

In an interview with the International Herald Tribune, Dr Mahathir said that the police response to further demonstrations by Mr Anwar's supporters would depend on whether there was further violence.

"To put a stop to violence you cannot use kid gloves," he said. "You have to be a little rough."

Our correspondent says there are clear signs that the authorities are moving to silence those suspected of links to Mr Anwar.

Students warned

Police have banned all meetings of Mr Anwar's supporters

Meanwhile, reports in Malaysian newspapers say police have banned all meetings by supporters of Mr Anwar.

Police Chief Tan Sri Abdul Rahim Noor said with the Commonwealth Games now over, police would focus their attention on what has become known as the 'reformasi' (reform) movement.