The opposition National Salvation Front (NSF) has condemned a recent spate of violent attacks on peaceful protesters.
In a statement on Sunday, the front claimed organised violence, including sexual attacks using knives on female protesters, was designed to prevent people expressing their views.
President Mohamed Morsi, his government and the interior minister are responsible for the violence and torture, the front said. They have failed to protect peaceful protesters from attacks by militias and thugs, such as those carried out against women in Tahrir Square.
"These organised mob sexual assaults cannot be separated from the oppressive tactics [of the security forces] and the use of torture and intimidation against revolutionaries," read the statement.
Such tactics would not stop women from participating in Egypt's political life, it added.
Dozens of mob sexual assaults have taken place around Tahrir Square during recent protests. Many argue the attacks are systematic and organised.
On Saturday, the front issued a statement condemning police brutality and rejecting the accusation that the opposition is to blame for the escalating violence.
"The Egyptian people and the whole world witnessed the violence around the presidential palace [on Friday]. It coincided with successive statements by the Muslim Brotherhood's leaders accusing the Egyptian people, the peaceful revolutionary forces, and the National Salvation Front of inciting violence," read the statement.
"Those statements revealed aggressive intentions toward the people and the opposition. This was confirmed by the violence [on Friday] and the unjustified use of brutal violence [by the police] … The brutal stripping and dragging along the ground of an unarmed man is an inhuman act [by the police] that involves unacceptable humiliation and is no less horrible than the assassination of his fellow martyrs," it added.
The NSF confirmed it would not engage in a dialogue with the president until the "blood baths" have stopped and those responsible are put on trial.
It further demanded an impartial judicial investigation into the killing, torture, and detention without trial of protesters, and "a fair trial for all those responsible, starting with the president, the interior minister and all his partners in those crimes."
The NSF called on Egyptians to demonstrate peacefully to demand their rights and "in defence of Egyptian dignity."