Abdul Gani Patail told the country’s highest court that Prime Minister Abdullah Ahmad Badawi had ordered their arrest under the tough Internal Security Act (ISA) following a comprehensive investigation.

“The prime minister... had ordered their arrest (last December) upon a thorough police investigation which deemed them as a threat to national security,” he said.

Gani was responding to arguments by the lawyer of the five, who said on Wednesday that their detention was illegal and demanded their immediate release.

“To say that there was no evidence, that the minister acted on his own frolic, was absolutely wrong. I urge the court not to accept that,” he said.

The five, including a newly elected state lawmaker, enraged the government in November by mounting a mass rally alleging discrimination against minority ethnic Indians in Malaysia, which is dominated by Muslim Malays.

Police used tear gas, water cannon and baton charges to break up the Hindraf street protest, which drew 8,000 people.

The five are being held in the Kamunting detention centre in northern Perak state.