The demonstrators moved in after police scaled down a show of armed might in the capital ahead of Mr Anwar's trial which begins on Monday.

The police staged a show of force

The rally took place as the Malaysian authorities said they were preparing new charges of sexual misconduct against Mr Anwar, in addition to the 10 existing charges of corruption and sodomy.

The Attorney-general, Mohtar Abdullah, said Mr Anwar's trials would continue at least until June next year.

He didn't specify the nature of the new charges but said they would be brought under a law for the protection of women and girls.

Mr Anwar says police beat him up in custody

Saturday's protest was in the same area where violent clashes erupted last Saturday.

Some 600 demonstrators shouted slogans demanding the resignation of Prime Minister Mahathir Mohamad.

They also chanted "Reformasi," the pro-reform slogan identified with Mr Anwar.

Mr Anwar was sacked from the cabinet in September and later arrested under the Internal Security Act for allegedly inciting followers to violence.

Wave of protests

Mr Anwar's arrest and trial has sparked a wave of protests in the capital and growing calls for political reform.

Security in Kuala Lumpur was stepped up on Saturday in anticipation of more demonstrations.

Hundreds of police carrying automatic rifles circled the Petronas Twin Towers, the world's tallest building.

A surveillance helicopter hovered overheard and police trucks with water cannons stood by.

Last week's riot - the first in nearly 30 years

A full-scale riot broke out for the first time in nearly three decades last weekend, after riot police fired tear gas and water cannons at a neighborhood mosque.

Protesters retaliated by hurling stones and bricks.

Riot police have threatened to come down hard on anti-government protesters, who said they would target new areas in their demonstrations.

"Our uppermost concern is to ensure public order in or outside the court and we reckon the trial will proceed smoothly," said police chief Abdul Rahim Noor.

On Friday, Dr Mahathir accused the foreign media of portraying the government as ''stupid'' and incapable of administering the country.

He said protesters were intentionally challenging the police to enable foreign news photographers to portray the local force as brutal.