Suaram said Dr Mahathir, as home minister, must accept full responsibility for rioting on Saturday in the capital, Kuala Lumpur.

The BBC's David Willis: The first time in two months of pro-democracy protests that violence has erupted

It condemned what it called the violent and repressive actions of the Malaysian police in dealing with the protests and said the situation was totally mishandled.

"He cannot ignore the legitimate discontent of the people," said a Suaram spokesman.

"We call upon the prime minister to resign so that a general election can be held."

The call was backed by several opposition parties. The main opposition group, the Democratic Action Party, also called for an independent and public inquiry into the violence.

Some protesters were forcefully removed by plain clothes officers

More than 240 people were arrested in clashes between police and supporters of the jailed former Deputy Prime Minister, Anwar Ibrahim.

It was the first time since demonstrations for political change began last month that protests had ended in violence.

Police used tear gas and water cannon after a large crowd gathered chanting for reform.

The protesters responded by throwing rocks and stones, and a series of clashes followed.

Police in balaclavas chased people through department stores, beating some.

Mahathir: 'Not intimidated'

The prime minister himself condemned the protests and said his government would not be intimidated.

"The groups calling themselves reformists seeking to uphold justice are the ones who are breaking the law," he was quoted as saying.

Protesters were sprayed with a mix of water and chemical irritant

He said nobody benefited from the clashes, only the country's image suffered.

Dr Mahathir said the protesters were cowards who used women and children as shields.

"Don't blame the government if children are burnt during the rioting, as the authorities have discovered Molotov cocktails and kerosene at the scene," he said.

David Willis in Kuala Lumpur: "I was caught up in this"

Demonstrations in support of Mr Anwar have been declared illegal and several people have been arrested in a series of anti-government rallies that followed Mr Anwar's detention.

Most have since been released on bail, but police are warning protesters that they could face arrest under the Internal Security Act, which allows for indefinite detainment without trial.

Mr Anwar was sacked as finance minister in September

Mr Anwar was sacked by Dr Mahathir last month. He was later arrested and, he says, beaten by police.

He faces trial next month on four out of 10 counts of corruption and sodomy - charges he says are part of a high-level political vendetta.

One of the two main witnesses against him has said he was stripped, humiliated and brainwashed in custody before telling police he had committed sodomy with Mr Anwar.