Egypt’s interior ministry confirmed reports of deaths during what it said was an escape attempt by detained Muslim Brotherhood elements , saying 36 people had been killed.
In a statement released on Sunday night, the ministry said that the detainees had been killed by asphyxiation due to teargas and “crowding.”
Egyptian security forces had said earlier on Sunday that they had aborted an escape attempt by over 600 detained supporters of ousted president Mohamed Morsi at Abu Zaabal prison north of Cairo  on Sunday.
Egypt’s state news agency MENA reported that an armed group attacked the Abu Zaabal prison while a vehicle transferring some of the detained Muslim Brotherhood supporters was arriving in an attempt to free them and other prisoners, but security forces were able to protect the vehicle.
The report had said that some of the perpetrators were shot and some of the prisoners inside the vehicle suffocated from teargas fired at the scene and were being treated.
On Saturday, Egypt’s interior ministry announced it had arrested 1,004 Muslim Brotherhood  “elements” on Friday, when large demonstrations  were held demanding Morsi’s return to power and condemning the violent dispersal of pro-Morsi sit-ins on Wednesday.
Official health ministry figures say the death toll has reached at least 800 deaths since Wednesday’s dispersals.
The interior ministry has started a wave of arrests of prominent Islamist figures in several governorates, including Cairo, Alexandria and Suez.