Shiites face fast-tracked martial courts, continued detention of hundreds, demolition of mosques and arbitrary dismissal of employees in the kingdom, they say.
At least 567 people, including 38 women, remain in detention, former MP Matar Matar told AFP, out of around 1,000 people rounded up after security forces quelled the protest on March 16.
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"We are in touch with international organisations to highlight the systematic violations by the authorities," he said, claiming the government was taking advantage of "international silence" over the violations.
"This fast campaign shows that authorities are trying to use this time that is available as much as possible ... No one knows when the international silence about Bahrain will end," Matar said.
He also expressed fears that seven Shiite protesters may be sentenced to death by a military court on Thursday over charges they killed two policemen in clashes as the Shiite-dominated protest was crushed.
The Bahrain Centre for Human Rights (BCHR) put the number of detainees at 817, including 71 women in a clear breach of tradition in the conservative Muslim Gulf where women embody the honour of a family.
"This is a new phenomenon in Bahrain," said BCHR head Nabil Rajab.
One woman who spoke to AFP said she was threatened with rape if she did not confess to taking part in protests.
"You'd better confess. Otherwise, I'd take you to the other interrogation room where men would make you talk," she said, quoting an officer's threat.
The woman was dragged from her workplace along with other Shiite colleagues. In the bus to the police station, policewomen slapped their faces and made them chant pro-monarchy slogans, she said.
She asked AFP not to disclose details about her job because police warned them not to talk about their ordeal while in custody.
The woman said she eventually confessed to taking part in demonstrations at Pearl Square, epicentre of the anti-regime protests, and also to protesting at work.
She said she shared a cell with several doctors, nurses and teachers. While being released, she said she saw teenage female students being dragged into a police station and beaten by policewomen.
Bahraini authorities have been condemned by several international rights groups for clamping down on medical staff, mainly at Manama's Salmaniya Medical Complex, with medics punished for siding with protesters.
"They used to punish us psychologically by opening a door leading to the men's section of the police station so we could see them being beaten. We would hear their screams under torture," she said.
Although security forces showed restraint in driving protesters from Pearl Square, the authorities later unleashed police on Shiite dissidents nationwide.
Matar, who quit parliament along with 17 other MPs in the Al-Wefaq Shiite opposition group in February in protest at violence against protesters, also spoke of Shiite employees being sacked if said to have taken part in demonstrations.
"Police raid medical centres and separate employees based on their sects, then order Shiites to stand by the wall and put their arms up... while masked informers point out" those who joined the protests, he said.
More than 1,000 Shiite employees had been fired, he said.
The government admits dismissing workers. On Tuesday, the health ministry said it had referred for prosecution 30 employees among those suspended because of "recent events", after a probe found that they committed acts that "appeared criminal".
Even sports professionals were targeted. An investigatory committee has suspended 150 players, coaches and staff over their alleged involvement in protests.
Meanwhile, the authorities have demolished many Shiite places of prayer and old mosques, saying they were built without authorisation.
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