Hundreds of detained supporters of deposed president Mohamed Morsi have been denied their legal rights, said Amnesty International in a statement issued Wednesday.
Detainees told the rights organisation that they were beaten upon arrest, subjected to electric shocks or hit with rifle butts, according to the statement.
Hassiba Hadj Sahraoui, Deputy Middle East and North Africa Programme Director at Amnesty International, warned that such cases "risk being seen as mere retribution rather than justice."
"At this time of extreme polarisation and division, it is more important than ever that the office of the Public Prosecutor demonstrates that it’s truly independent and not politicised," added Sahraoui.
While release orders were granted to some 650 suspects, an unknown number remain in detention "due to their inability to pay bail ranging from 1,000 to 5,000 Egyptian pounds ($140-$700)," according to Amnesty.
Over 400 Morsi supporters were arrested on Monday night following violence that erupted during their rallies in several districts in Cairo.
Police forces clashed with pro-Morsi demonstrators in Ramses Square in downtown Cairo on Monday firing teargas and birdshot to clear the square.
Detainees face charges of rioting and vandalising private property.
Following Monday's clashes, the Muslim Brotherhood issued a statement accusing the police of returning to its brutal practices prior to the January 25 revolution. The Brotherhood statement further warned of a possible return to a "dictatorship police state" after a "bloody coup d’état."
Establishing trust in the justice system will be impossible if only supporters of Morsi and the Muslim Brotherhood are targeted while security forces are absolved of responsibility for unlawful killings and their failure to protect protesters from violence," said added Sahraoui.
Amnesty also quoted Mostafa Ali, a former detainee, who said that during his detention he and his wife were forced to crawl on broken glass by Egyptian security forces, adding that they were beaten and given electric shocks.
Ali and his wife were arrested during last week's Republican Guard clashes that left over 50 killed and 261 injured.
The statement also denounced the detention of the deposed president Morsi.
On Wednesday, Egypt' military spokesman asserted that Mohamed Morsi is not being detained because there is no court order against him, adding that the army has been protecting him amid widespread instability.