CAIRO — Around 20,000 prisoners, opposing Egypt's current authorities, are expected to start a hunger strike inside their prison cells on Friday in protest against alleged mistreatment by their prison administrations, an Egyptian rights activist said Thursday."More than 20,000 prisoners will start a week-long hunger strike in more than 114 detention centers and prisons," Haytham Abo Khalil, the director of Victims Center for Human Rights, told Anadolu Agency.He added that the prisoners would stage the strike in protest against what they describe as the "mistreatment" inside the nation's prisons.Abo Khalil said by staging the strike the prisoners want to invite attention to their suffering.Egyptian prison authorities could not be reached for comment or verification of the claims.A recent report by the Egyptian Center for Economic and Social Rights (ECESR), a local NGO, documented over 21,000 cases of individuals who had been subject to prosecution since Morsi's ouster by the military last July.There have been reports of widespread and systematic mistreatment and torture being carried out in Egyptian detention facilities.However, the Egyptian authorities have repeatedly denied reports of torture being used against detained supporters of ousted president Morsi and his embattled Muslim Brotherhood group.The military-backed government also denies the presence of any "political" prisoners in the nation's jails, saying the thousands arrested since Morsi's ouster face criminal charges.