Mohamed Morsi was reportedly being held on charges he killed a soldier and conspired with the Palestinian militant group Hamas, as the Egyptian city of Alexandria saw seven killed and over 100 injured in clashes Friday.
The former president, who has not been seen nor heard from since he was ousted by Egypt's military on July 3, has been ordered detained for at least another 15 days, according to Egyptian state media.
A report by the state news agency said investigating judge Hassan Samir had confronted Morsi with evidence during his questioning, though it did not say when or where he had been questioned.
Morsi is being held pending investigations that he helped Hamas carry out "anti-state attacks" on police stations and jails during the 2011 revolution that toppled another former president, Hosni Mubarak.
Morsi was one of several members of the Muslim Brotherhood who escaped from the Wadi el-Natroun prison during the 18-day revolt. The charges filed Friday allege that he plotted with Hamas to mount the jail break.
Speaking to Agence France-Presse, Muslim Brotherhood spokesman Gehad el-Haddad dismissed the accusation as "ridiculous" and compared it to "a retaliation from the old regime."
The Associated Press cited Brotherhood officials as saying the jailbreak was aided by local residents, not foreigners like Hamas.
Hamas, meanwhile, condemned Egypt's allegations of Morsi's connection to Hamas.
"Hamas condemns this move since it is based on the premise that the Hamas movement is hostile," spokesman Sami Abu Zuhri told AFP. "This is a dangerous development, which confirms that the current powers in Egypt are giving up on national causes and even using these issues to deal with other parties — first among them the Palestinian cause."
The revelation of charges came as pro- and anti-Morsi supporters held rival street protests, raising the specter of more violence in the capital and beyond.
Army General Abdel Fatah al-Sisi had called for mass demonstrations Friday to oppose "terrorism" and provide the military with a "mandate" to maintain order and prevent violence.
Official leaflets addressing Morsi supporters were reportedly dropped on the Rabaah al-Adawiya Mosque in Cairo, reassuring them of their safety:
“We are not against you so don’t be against us. Don’t raise your weapons in the face of your brothers, don’t destroy, don’t burn, and let us all be together against killing, violence and terrorism."
However, Sisi struck a tougher tone, saying any violence or terrorism would be "dealt with decisively and with force," the AP wrote.
The Brotherhood also called for mass protests Friday and saw a large pro-Morsi, anti-coup turnout.
Clashes between rival protesters were reported in Alexandria, resulting in seven deaths and 100 people injured, the health ministry said, according to The Associated Press.
Some witnesses reported seeing protesters who were both anti-Morsi and anti-military.