(AFP) Police chief Norian Mai said today a mass opposition protest planned for Saturday outside the deputy premier's home would be illegal and warned people against attending.

"Don't go, don't join. It is illegal and unlawful," Norian told a press conference.

Opponents of Malaysia's controversial Internal Security Act (ISA), which has been invoked to detain four opposition activists without trial for up to two years, say they will hold a peaceful mass protest at the official residence of deputy Prime Minister Abdullah Ahmad Badawi.

Abdullah, who is also Home Affairs minister, signed the detention orders under the feared ISA.

Under tough public assembly laws, police can declare any unauthorised gathering of more than four people illegal.

Offenders can face up to a year in jail.

Two still detained

The Human Rights Commission (Suhakam) has investigated allegations of police brutality when a protest was broken up last November but has not released its findings.

Since then police have generally adopted a softer line.

The four activists, who have been transferred to a detention camp in Kamunting, Perak, are among 10 supporters of jailed ex-deputy premier Anwar Ibrahim who were arrested under the ISA between April 10 and 26.

Three of the four are leading members of the opposition Keadilan party headed by Anwar's wife.

Two other ISA detainees are still in police custody, two have been ordered freed by a high court judge and two have been voluntarily released by police.

Asked if the two still in police custody would be freed soon, Norian said it was up to the Home Affairs minister to decide.