At least 36 prisoners, alleged members of the Muslim Brotherhood, died Sunday in a clash that broke out when a group of armed men attacked a police convoy that was transporting 612 Islamist prisoners to the Abu Zabal jail in northern Cairo.

According to what security officials told state-run television and the official Mena news agency, the 36 prisoners were killed in the gun battle that erupted near the prison between the police who were transporting them and the armed group that was trying to free them.

The police convoy was transporting the 612 Islamists to the Abu Zabal prison.

Mena reported that during the attack a police officer was taken hostage by the Islamists, but he was released shortly thereafter and taken to a hospital.

The arrested men had been taken into custody in the disturbances last Friday in Cairo's Ramses Square, where a confrontation broke out between Islamists and police, with the former violently attacking a police station.

The Freedom and Justice Party, the political arm of the Muslim Brotherhood, called the deaths of the detainees a "terrible bloody massacre."

Police used tear gas - which reportedly injured some of the prisoners - during the attack on the convoy and were able to prevent the armed group from freeing any of the prisoners.

Some of the attackers died in the shootout, according to the official cited by Mena, but he did not provide a casualty count.

In another incident, two police officers died and two others were seriously injured when alleged members of the Muslim Brotherhood opened fire on their convoy along the highway linking Cairo with the city of Ismailiya, on the Suez Canal.

Tension has increased dramatically in Egypt since last Wednesday, when security forces dislodged two Islamist camps in Cairo.

Authorities so far have not provided a comprehensive count of the fatalities over the past five days of violence, but a tally of official figures released piecemeal to date places the tentative number of deaths at about 900.

Supporters of deposed President Mohammed Morsi on Sunday staged marches at different spots around the capital to protest the military coup that removed him from power, and army commander Abdel Fatal al Sisi declared that the authorities will not allow themselves to be overcome by the violence. EFE