Alaa Abdul Fattah, an Egyptian blogger, was arrested by the authorities under the accusation of calling over protests in defiance of a new law that restricts demonstrations. He took part in a rally outside the Upper House of Parliment.
Protesters were demanding the banishment of the new law that bans unauthorised demonstrations.
Abdul Fattah played a leading role in the 2011 revolt against Hosni Mubarak, a governor of Egypt.
Abdul Fattah did not deny the charge. Another 24 activists were detained at the protest and will remain four days in custody under the suspicion of various charges.