Activist Mamdouh Hamza (Photo: AL-Ahram)
Mamdouh Hamza returned to Egypt from Switzerland to face questioning over charges he incited violence around Egyptian Cabinet offices in Cairo last December.
Government prosecutors investigating the clashes between protesters and security forces, which left17 dead, had summoned Hamza as well as presidential hopeful Ayman Nour for questioning last Tuesday.
The prosecutors also issued a travel ban against Hamza, who was in Zurich for medical treatment at the time the summons was issued.
The investigation came after the names of Hamza and Nour were mentioned during testimonies as allegedly responsible for inciting the clashes and burning of public buildings, including the historic Egyptian Scientific Institute.