Human rights groups are pressing for their release while 16 of the detainees have threatened to go on hunger strike.
The New York-based Human Rights Watch on Thursday urged the government not to renew detention orders on seven men held for alleged involvement in "terrorist activities" when their first two-year terms expire on Friday.
"After two years, the government's claim that they must hold these seven men without charge in order to continue investigations no longer makes sense," said Sam Zia-Zarifi, deputy director of Human Rights Watch's Asia Division.
"The Malaysian government has taken advantage of the 'war on terror' to justify holding these men indefinitely," Zia-Zarifi said.
"Given the sad history of abuse under the Internal Security Act, no one can take the Malaysian government at its word. These seven men deserve their day in court."
The seven are allegedly linked to the Jemaah Islamiyah (JI) network blamed for the Bali bombing which killed 202 people in October 2002.
"Given the sad history of abuse under the Internal Security Act, no one can take the Malaysian government at its word"
deputy director, Human Rights
Watch, Asia division
Six other alleged JI members who had completed their first two years in prison had their detention orders renewed last Saturday.
The 13 are among more than 90 suspected members of armed groups held in Malaysia under the Internal Security Act (ISA), which allows for two-year detention orders to be renewed indefinitely.
Sixteen others accused of belonging to the local Malaysian Militant Group (KMM) are threatening to go on hunger strike next week if they are not freed, the Voice of the Malaysian People (Suaram) said.
The detainees include Nik Adli, the son of the spiritual leader of the hardline opposition Islamic Party (PAS) Nik Aziz Nik Mat, which presents the main challenge to the government of Prime Minister Abd Allah Ahmad Badawi in elections expected within a month.
"They will launch their hunger strike on 1 March if the government does not meet their demand," Suaram spokesman Yap Swee Seng said.
Some of the 16 have been accused of serving with armed movements in Afghanistan and in neighbouring Indonesia and police allege they planned to overthrow the Malaysian government.
Yap said the men, who deny the allegations, had written to Abd Allah, who is also the home (interior) minister, to press for their release.
All of them are being held at the Kemunting detention centre in northern Perak state under legislation first designed to fight a communist insurgency four decades ago.