"Ahmed Fouad Negm passed away. He was 84," Mohammed Hashem told AFP.
Negm spent a total of 18 years in jail for his strident criticism of former Egyptian presidents Gamal Abdel Nasser, Anwar Sadat and Hosni Mubarak.
He became recognised as a voice of protest in 1967 when he wrote poems on the Arab-Israel war, which were highly acclaimed.
During the 2011 anti-Mubarak revolt, protesters often recited his revolutionary poems at Cairo's iconic Tahrir Square- epicentre of the 18-day uprising against the former strongman.
Son of a police officer and a housewife, Negm was born in 1929 in the Egyptian city of Sharqia and was one among 17 brothers.