Bahrain has begun freeing political and other prisoners, including about 25 "prisoners of conscience" accused of seeking to overthrow the kingdom's Sunni Muslim monarchy.
Proceedings against other prisoners were halted, the Bahrain Center for Human Rights said.
King Hamad bin Isa al-Khalifa pardoned the political prisoners Tuesday in a gesture toward opposition activists seeking an elected government in Bahrain, where seven people were killed and hundreds wounded in protests last week.
More than 100,000 people marched in the capital Manama Tuesday, in what organizers called the largest-ever pro-democracy demonstration in the majority-Shiite island nation of only 500,000 citizens run by a Sunni elite.
Among those released included the prominent human rights activist Ali Abdulemam, who runs bahrainonline.org; Abdul-Ghani Khanjar, a member of Committee for the Victims of Torture; and Mohammed Saeed, who works with the Bahrain Center for Human Rights.
Several prominent Shiite clerics, including Abduljalil Al-Sengais, spokesman of the Haq Movement for Civil Liberties and Democracy, were also reportedly released.
The releases bring to about 100 the total number of political detainees so far released, Nabil Rajab of the Bahrain Center for Human Rights was quoted as saying. But, he said, about 400 people are still detained on politically inspired charges.
"Allowing the people to protest and releasing those people are positive moves," Ibrahim Mattar of the main Shiite Wefaq party told Reuters, saying more than 100 prisoners had been released before dawn, but dozens remained in jail. However, those released included 21 common criminals, he said.
Opposition groups were waiting for the royal family to accept the principle of a constitutional monarchy before they would enter into a dialogue.
Meanwhile, Hamad has visited ally Saudi Arabia for talks on the unrest, according to the Washington Post.
Like the tiny Bahrain, OPEC heavyweight Saudi Arabia also has a significant Shiite population that has long complained of oppression by the Sunni rulers.
There are concerns that Bahrain's uprising, now in its second week, could spread to the Saudi kingdom, whose absolute rulers permit few political freedoms.
Mass protests erupted in the kingdom last week, and during the march in Manama on Tuesday, chants of "No Shia, No Sunni, only Bahraini" and "The regime must go" could be heard.
The turnout was led by ambulance workers involved in rescuing some of those injured in the assault by security forces last Thursday in Pearl Square, which has been the epicenter of the Shia-dominated protest movement.
Because of the protests, Formula 1 canceled the season-opening race that was scheduled for March 13 at Sakhir. Bernie Ecclestone said Thursday he would waive the race-hosting fee that Bahrain would normally owe Formula One Management.