(AFP) - Malaysia has hit back at US criticism of its detention without trial of opposition activists, saying the action was not taken "for fun".

The country does not need outside interference in its internal affairs, Deputy Prime Minister Abdullah Ahmad Badawi said.

"This country is our responsibility ... we take action against anyone who breaks the law," Bernama news agency late yesterday quoted him as saying.

"It (detention) is not without reason. It is appropriate that we take action ... it is not done for fun," added Abdullah, who is also home minister.

The US State Department said on Tuesday it was "deeply concerned" at the decision to detain four opposition activists for up to two years.

Spokesman Richard Boucher said the actions "seem intended to prevent the detainees, against whom there are no criminal charges, from exercising internationally recognised rights of free speech, political expression, and assembly."

The four are among 10 supporters of jailed ex-deputy premier Anwar Ibrahim who were arrested under the Internal Security Act (ISA) between April 10-26.

Three of the four are leading members of the National Justice Party headed by Anwar's wife.

Abdullah said most Malaysians understand the need for the ISA.

Mass protests

Opponents say the law, which allows indefinite detention without trial, is used to suppress peaceful opposition to Prime Minister Mahathir Mohamad's rule. They plan a mass protest this Saturday outside Abdullah's house.

Abdullah said he would leave the protest to police to handle. "If they do that without proper permit, then I am sure that the police will act against them," The Star quoted him as saying.

Mahathir and police chief Norian Mai have said Anwar's supporters planned to use explosives and weapons in street demonstrations to topple the government. No evidence of this has been made public.

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.

Anwar is serving a total of 15 years in prison for abuse of power and sodomy. He says he was framed to avert a political challenge to Mahathir, who denies the allegation.

Newspapers today reported that former police chief Rahim Noor, who was jailed for two months for beating a blindfolded and handcuffed Anwar in his cell in 1998, is expected to released on Saturday after serving 40 days.

They quoted senior officials as saying it was normal procedure to grant one-third remission of sentence for good behaviour.