Hamdan Adnan, of the National Human Rights Commission, led a four-member team on Saturday to investigate allegations of assault against the detainees at the Kamunting detention camp in northern Perak state. Hamdan said tension was high in the camp.
On Wednesday 12 inmates and 18 guards were injured in a scuffle sparked by detainees trying to prevent a spot check which turned up a cache of homemade weapons.
"Most of them are alleged terrorists and some have been there for more than three years," said Hamdan.
"They are very resentful because they have not been charged and they claim to be innocent. They want their freedom.
"What is important is to charge them in court or to release
Malaysia is holding more than 80 alleged suspects under the controversial Internal Security Act (ISA), which allows indefinite detention without trial.
Rights groups have urged the government to scrap the ISA but officials maintain it is needed as a first line of "defence against terrorism".
During his five-hour visit to Kamunting, Hamdan said he was briefed by prison authorities on Wednesday's scuffle which injured four Malaysians, six Indonesians and two Filipinos, allegedly involved with the Jemaah Islamiya (JI) network - as well as 18 guards.
Rights groups want the Internal
Security Act to be dropped
Hamdan said prison authorities told him some of the detainees had skills like MacGyver, referring to a character from a US television series who has the ability to fashion weapons from everyday objects.
Hamdan was shown an exhibit of banned items found in the dorms, including 13 handphones, condoms, gardening tools, pipes and badminton racquets fashioned into weapons.
"A number of them are highly skilled and educated. Some of the prison guards said they felt threatened and intimidated for a long time. There is a lot of tension there. The government needs to beef up security in Kamunting," Hamdan said.
He said he would propose in his report to the National Human Rights Commission (Suhakam) that an independent hearing be held to verify claims by some of the detainees that they had been beaten up.
Another rights group, the Abolish ISA Movement, echoed his call for an independent investigation into allegations by some detainees that they had been handcuffed, forced to strip, assaulted and ridiculed by wardens.
Families of five JI detainees, including ex-army officer Yazid
Sufaat, who has been detained since November 2001 for alleged links to the 11 September hijackers, lodged complaints on Saturday with police that they were abused.