The killed include 700 policemen and 550 civilians killed between June 30, 2013 and December 31, 2014, according to head of the National Council for Human Rights Mohammed Fayeq.
Prisons in Egypt are filled to 160 percent capacity, while holding cells are overfilled by four times, Fayeq was cited as saying by the Guardian on Sunday.
Ousted Egyptian President Mohamed Morsi is currently serving a 20-year prison term for inciting the killing of protesters during mass riots outside the Federal Palace in Cairo in December, 2012.
On May 16, 2015, a criminal court in Cairo sentenced Morsi to death for leaking state secrets and orchestrating a prison break during a 2011 uprising against Egypt's previous leader, Hosni Mubarak.
Morsi was deposed by a military coup following days of massive protests against his rule and that of his Muslim Brotherhood party in 2013.
Former army chief and current President Abdul Fattah Sisi has since outlawed the Brotherhood calling it a terrorist group and arrested scores of Morsi supporters, including those behind the 2011 uprising against Mubarak.
