Egypt's general prosecution ordered that 312 people detained during pro-reform protests on Thursday be remanded in custody for 15 days pending an investigation, a judicial source said.
Those being held include Muslim Brotherhood spokesman Issam al-Aryan and former MP Mohammed Mursi. According to AFP, charges included participation in demonstrations, which are not allowed in Egypt, as well as slandering the president of the republic, resisting the authorities and obstructing implementation of the law.
The detainees have also been accused of attacking police and preventing them from carrying out their duty, disrupting traffic and chanting hostile slogans.
Some 400 people were detained across the capital, according to a senior official from the opposition Muslim Brothers.
Hundreds of protesters had scattered across Cairo Thursday to express support for judges Mahmud Mekki and Hisham Bastawissi, who were referred to a disciplinary board after accusing colleagues of electoral fraud.
