Malaysia's Prime Minister Abdullah Ahmad Badawi on Wednesday warned protesting ethnic Indians that the government will invoke the Internal Security Act, under which a person can be held without trial for an extended period of time.

"When it is appropriate it will be used," Badawi, who is also the internal security minister, was quoted by the national news agency Bernama as saying.

He said under current circumstances, the government was leaving it to the police to evaluate the situation and take appropriate measures to guarantee peace and security.

Badawi's remarks comes in the wake of a massive street demonstration on Sunday by ethnic Indians in Kuala Lumpur who complained of being marginalised since the time their ancestors were brought from Indians by ethnic Indians here as indentured labourers and exploited, an allegation denied by the Malaysian government.

"The ISA is a preventive measure to spare the nation from untoward incidents that can harm the prevailing peace and harmony, and create all sorts of adverse things. So, I do not know (when to invoke the ISA), but ISA will be there. When it is appropriate to use it, it will be used," he said.

Badawi was responding to reports that several street demonstrations by the ethnic Indians will be held in the country soon.

Badawi said the suggestions to invoke ISA had in fact came from the people as a means to tackle street demonstrations.

"I am very surprised that the people want the ISA. I thought they never wanted the ISA," he said.

Malaysian police used tear gas and water cannons on Sunday to quell the protest by thousands of ethnic Indians who defied government warnings to stay away from a rally called by a Hindu rights group to march to the British High Commission protesting against alleged marginalisation.

The Hindu Rights Action front (Hindraf) wanted to hand over a memorandum signed by over 100,000 ethnic Indians demanding Queen Elizabeth II to appoint a Queen's counsel to represent the Indian community in a class action suit against the British government for bringing Indians as indentured labourers to then Malaya and exploiting them.

Hindraf has also asked for a compensation of four trillion US dollars from the British government.       

Malaysiakini, an independent news website, said: 'Furthermore, the suit sought a declaration that the Reid Commission Report 1957 failed to incorporate the rights of the Indian community when independence was granted, resulting in discrimination and marginalisation to this day."