Cairo Criminal Court canceled on Thursday the release of Wasat Party leader and former MP Essam Sultan.
The court ordered Sultan's detention for another 45 days pending investigation over charges of torture at the Rabaa al-Adaweya sit-in.
A court had ordered Sultan's release on Wednesday, but the prosecution challenged the ruling.
Sultan faces charges of inciting the killing of three citizens, in addition to allegedly inciting violence, torture and setting fire to a state building.
The defense had asked for the defendant's release based on lack of evidence and argued that charges against Sultan were baseless.
Meanwhile, the prosecutor argued that evidence against Sultan was available and the court canceled his release.
Edited translation from Al-Masry Al-Youm