Two members of a former opposition party were among the more than 140 people released from prison by Bahraini authorities. Former lawmakers Matar Matar and Jawad Fairuz, members of the former al-Wefaq opposition party were tortured while in custody, Matar was quoted by CNN as saying.
His party took 20 percent of the seats in Parliament in 2009 elections. Bahrain in April outlawed the party, the country's largest Shiite political party, and the opposition Islamic Action Society for breaking the law during mass protests and for inciting violence.
He said security forces didn't torture detainees so much as to get information as to "send a message" that they have a "green light" to do whatever they want.
Bahrain Center for Human Rights President Nabeel Rajab was quoted as saying as many as 98 percent of those held by state security forces were abused in some fashion.
"No one was immune," said Rajab. "Very rarely will you find someone who was not abused."
Bahrain in early July started a dialogue process meant to examine possible improvements in the political structure. The government earlier received praise for transferring some trials from a military tribunal to civilian courts.
The Sunni-led kingdom was condemned for its violent response to a Shiite uprising early this year.