Malaysian police used teargas and water cannon to disperse an estimated 10,000 protesters on Saturday in the capital, Kuala Lumpur.
Security forces arrested 589 people who were protesting against a law allowing detention without trial.
Prime minister Najib Razak denounced the protests, saying he has already agreed to review the Internal Security Act.
The BBC reports the protest started after prayers finished at the national mosque on Saturday. It was attended by opposition leader Anwar Ibrahim, who has been imprisoned under the law in the past.
Anwar was dismissed as deputy prime minister in 1998 and imprisoned on corruption and sodomy charges.
Twelve detainees are currently being held under the ISA.
Most are suspected of having links to terror groups including Jemaah Islamiah, which carried out the Bali bombings that killed 202 people in 2002.