Abdullah's warning came following allegations by authorities that the members of the Hindu Rights Action Force (Hindraf), which is spearheading the anti-government agitation against the alleged marginalisation of ethnic Indians, are linked with 'terrorists' groups including LTTE.

"My instructions to the police is that the group should be monitored. Internal Security Act is an option. I will decide when the time is right. If they are deemed (as a threat to national security) we will know what to do," the New Straits Times quoted Abdullah as saying.

ISA allows for years of detention without trial.

Abdullah, who is also the Internal Security minister, said he was aware of Hindraf canvassing for support and help from terrorist groups and local gangsters.

Meanwhile, a senior leader in the Prime Minister's Department has said the Malaysian Government had Sri Lanka's LTTE and India's RSS as the overseas groups linked to Hindraf.

Mohamed Nazri Aziz was quoted by the Star newspaper as saying that this was deduced from statements of Hindraf leaders, who went abroad to garner support, that they would meet LTTE leaders.

"As we know, the LTTE has been declared a terrorist group by the United Nations and the United States. If it is true that Hindraf leaders have links with them, Hindraf is also a terrorist group," he said.

The paper did not make any further reference to Nazri's comments on RSS.

The country's police chief Musa Hassan was reported to have said on Friday that there were signs lately that Hindraf was trying to garner support from terrorist groups.

He said Hindraf had also set up a fund by misleading the public into believing that the money was to finance its activities.

Opposition party DAP leader Karpal Singh felt that Hindraf leaders should be given the opportunity to explain the reasons behind the demonstration.

He added that the presence of thousands of Indians at the demonstration was cause for concern and reason enough to assume that the problems of the community ought to be addressed, the Star reported.

Meanwhile, the Sultan of Selangor said Hindraf's actions had incited hatred and damaged Malaysia's image by taking its campaign overseas.

Sultan Sharafuddin Idris Shah said he was unhappy at Hindraf supporters carrying banners and pictures of Queen Elizabeth II during the recent protests.

"Why were they displaying her pictures and asking her to intervene in Malaysia? They can always bring their case to the Government and the Yang di-Pertuan Agong," he told the Star newspaper.