Bahrain's largest opposition group on Tuesday dismissed a government statement acknowledging "instances" of abuse, saying the repression of mainly Shiite anti-government protesters is "systematic."
Meanwhile, three rights groups issued a report documenting acts of repression, on the eve of the planned release of a report by an independent commission of inquiry into the kingdom's crackdown on dissent.
The opposition Al-Wefaq said in a statement the Sunni-dominated government is trying to escape responsibility for "violations leading to numerous fatalities and hundreds of injuries on junior security personnel."
The Wefaq statement said the February and March bloody crackdown on protesters was "systematic" and the result of a "planned" government policy.
Al-Wefaq argued that the sheer number and nature of "abuses could not have taken place without prior knowledge and consent of influential officials," adding that the "ultimate responsibility lies with the top decision makers rather than junior officials and soldiers."
On Monday, the Manama government 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. Hundreds more were injured and detained.
Bahraini rights groups said in a report that 45 killings by security forces have been documented, three "attributed to the wrongful use of tear gas inside residential homes, which led to the suffocation of those unable to escape in time."
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International rights organisations have repeatedly accused the government of violating citizens' rights, citing allegations of torture, unfair trials, excessive use of force and violent repression.
The local rights groups reported 1,500 cases of arbitrary arrest, 1,866 of torture, 2,710 summary sackings and said 477 students have been expelled for allegedly taking part in the uprising.
"Society as a whole was targeted through the arbitrary arrest of doctors, nurses, teachers, academics, athletes, businessmen, and prominent opposition leaders who called for peaceful democratic change," said the report.
It added that up to "500 continue to be detained, the majority convicted to outrageous sentences in draconian military courts."
The report alleged that "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/authorised/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 said that "many victims, particularly the group of convicted doctors, have gone on the record and openly accused members of the royal family as torturing them directly."
"We will continue to demand, on behalf of the victims, that these perpetrators of human rights violations are held to account," they said.