The message from state-loyal media is confirmed by his sister.
43-year-old Alaa Abdel Fattah was a key figure in the revolt against President Hosni Mubarak, who was forced out of power in 2011. The regime critic was later imprisoned for spreading "false news" in a shared Facebook post about police brutality.
Both Alaa Abdel Fattah and his mother, Laila Soueif, have gone on hunger strike in protest against the imprisonment.