Egypt's prosecution ordered on Monday a 15-day detention for Wasat Party head Aboul-Ela Madi and spokesman Essam Sultan, less than one day after their arrest.
Sultan and Madi are accused of inciting violence by way of inflammatory speech directed at Morsi supporters camped-out in Nasr City's Rabaa Al-Adawiya mosque, which allegedly led to the fatal torturing of three citizens at the sit-in.
They are also accused of calling on Islamists to torch state institutions in Nasr City.
Both men were arrested early Monday in Cairo's Moqattam district and were transferred to Tora Prison on the outskirts of Cairo, where former president Hosni Mubarak and his two sons are also held.
The arrest of Madi and Sultan, who are staunch supporters of ousted president Mohamed Morsi, comes weeks after the detention of several leading Islamist figures in the wake of Morsi’s ouster.
The Wasat Party was founded in the late 1990s by defectors of the Muslim Brotherhood, the group from which Morsi hails.