Human Rights Watch today demanded Malaysia hold an investigation into police conduct during a weekend rally where tear gas and water cannons were unleashed on demonstrators.

The New York-based watchdog said that Prime Minister Abdullah Ahmad Badawi had effectively condoned the use of violence against the rally, which drew up to 40,000 protesters.

"Police responded by using chemical-laced water and tear gas to disrupt the orderly and peaceful marchers. Police also beat several retreating demonstrators. Some needed medical attention afterwards," it said.

Human Rights Watch condemned Abdullah's comments that he was "very happy" with the police action against the rally, which took place despite lacking the permit required under Malaysian law.

"If there was any doubt that the prime minister is more worried about political power than political rights, it was washed away with his defence of police actions against the marchers," said HRW's Asia director Brad Adams.

PM appeared to condone violence

"Badawi's remark was as good as saying outright that he condoned violence against political critics. He should rectify this impression by immediately calling for a royal commission to independently examine the facts."

The protest movement, a coalition of opposition parties and civil society groups known as Bersih is pushing for electoral reforms including a clean-up of the voting roll and an end to postal votes.

Protest leaders handed a memorandum to Malaysia's king during Saturday's rally and said on Tuesday they would also meet the country's nine state sultans to press for reforms.

Abdullah, who is expected to call snap polls early next year, has denounced the protesters for involving the king, who is highly respected but has a largely ceremonial role and usually stays out of politics.

SPECIAL REPORT: Bersih's Nov 10 mass rally