More than 1600 detainees in Jow central prison were subjected to torture, humiliating treatment and deprivation of basic rights during the first quarter of 2015, LHRD said in its report.
The report further said that 653 people, including 16 women and 119 children, were detained in the January-March period.
337 political prisoners were sentenced to a total of 2845 years, including 32 life sentences. Three were sentenced to death.
Sayed Hadi al-Mousawi, the head of the Liberties and Human Rights Department in Al Wefaq, said 2691 peaceful protests have been held across the country, including 1022 protests that were suppressed by the regime forces that used tear gas and shotguns.
The report added that 413 torture cases were recorded in the 3-month period.
559 house raids were also reported, the report said, adding that 278 were arrested during the house raids.
72 opponents, including 49 political and human right activists abroad, were stripped of their nationality, according to the report.
Referring to the continued detention of Sheikh Ali Salman, the secretary general of Al Wefaq, al-Mousawi called for his immediate release, saying the charges against him are baseless.
He also referred to the detention of Sayed Jamil Kadhem, the head of Al Wefaq Shura Council, and Nabeel Rajab, the prominent human rights activist, during the 3-month period.
Anti-government protesters have been holding peaceful demonstrations across Bahrain since mid-February 2011, calling for an end to the al-Khalifa dynasty.
Violence against the defenseless people escalated after a Saudi-led conglomerate of police, security and military forces from the Persian Gulf Cooperation Council (PGCC) member states – Saudi Arabia, Kuwait, the United Arab Emirates, Oman and Qatar – were dispatched to the tiny Persian Gulf kingdom on March 2011, to help Manama crack down on peaceful protestors.
So far, hundreds of protesters have been killed, hundreds more have gone missing and thousands of others have been injured.