Malaysia's lawmakers passed an anti-terrorism bill on Tuesday after more than 10 hours of heated debate over a law that reintroduces detention without trial, three years after it was revoked.
Opposition members of parliament proposed several amendments to the legislation, under which individuals can be detained for up to two years with two-year extensions thereafter, but it was voted through unchanged at 2am (1800 GMT Monday).
Malaysia last had detention without trial under the Internal Security Act (ISA), which was repealed in 2012 by Prime Minister Najib Razak under his reform agenda.
Phil Robertson of Human Rights Watch described the decision as "a giant step backwards for human rights in Malaysia".
"By restoring indefinite detention without trial, Malaysia has re-opened Pandora's Box for politically motivated, abusive state actions that many had thought was closed when the abusive Internal Security Act was revoked in 2012," he said in a statement on Tuesday.
The new law permits the police to arrest and detain individuals suspected of terrorist activities, with decisions for extension of detention made by a Prevention of Terrorism Board. The law skips the judiciary, disallowing the courts from having jurisdiction over decisions made by the board.
On Sunday, police continued their campaign against suspected militants, arresting 17 people aged between 14 and 44, including two who had recently returned from Syria.
Home minister Zahid Hamidi told Parliament on Monday that authorities suspect police stations and army camps were among the targets eyed by the militants as sources of firearms, the Star newspaper reported.
"This is a real threat and preventive measures must be carried out," Zahid said, according to the daily.
The Southeast Asian nation has arrested more than 60 citizens suspected of links with the Islamic State militant group and identified 39 Malaysians already in Syria and Iraq.