Bahrain's largest opposition group on Tuesday dismissed a government statement acknowledging "instances" of abuse, Gulf News reported.
Instead, opposition leaders say the repression of mainly Shiite anti-government protesters by the country's Sunni monarchy is "systematic."
The opposition group Al-Wefaq said in a statement that officials are trying to place responsibility for "violations leading to numerous fatalities and hundreds of injuries on junior security personnel."
Al-Wefaq argued that pervasive "abuses could not have taken place without prior knowledge and consent of influential officials," adding, "ultimate responsibility lies with the top decision makers rather than junior officials and soldiers."
On Monday, Manama acknowledged there had been "instances of excessive force and mistreatment of detainees," and said 20 officers are being prosecuted.
Authorities say 24 people, including four policemen, were killed in the month-long uprising, while the Shiite-led opposition puts the death toll at 30.
International rights organizations have repeatedly accused Bahrain's government of violating citizens' rights, citing allegations of torture, unfair trials, excessive use of force and violent repression.
Local rights groups reported 1,500 cases of arbitrary arrest, 1,866 of torture, 2,710 summary firings, and said 477 students have been expelled for allegedly taking part in the uprising.
Those groups allege "nearly 90 percent of those arrested experienced a form of physical and mental torture, humiliation and degrading treatment."
"Through the hundreds of testimonies of abuse and torture we have gathered, we have collected the names of at least 50 security officials who were identified by the victims as either carrying out the act of torture directly or who oversaw/authorized/ordered the act of torture," the groups alleged.
"There is substantial evidence to implicate nearly all of them through the direct identification by the victims of torture," it said.
However, "in the two cases where officers have been charged with causing the death of protesters, none have been convicted," they said.
The groups say "many victims, particularly the group of convicted doctors, have gone on the record and openly accused members of the royal family of torturing them directly."