36 Islamist prisoners have been killed during an attempted jailbreak in Egypt, as authorities continue their crackdown on supporters of ousted president Mohamed Morsi.
It brings the death toll after 5 days of violence to almost 800.
Senior European Union diplomats are set to hold emergency talks today to discuss any future action.
There are conflicting reports of how the prisoners died.
The Egyptian interior ministry said they had taken an officer hostage and died after suffocating on tear gas.
The army and police have sent reinforcements to the Abu Zaabal prison, the scene of Sunday's deadly jailbreak attempt, the official MENA news agency reported.
The Muslim Brotherhood, Morsi's once banned movement that backed his election victory in 2012, said 35 prisoners were killed, revising an earlier toll of 52.
"The murder of 35 detained anti-coup protestors affirms the intentional violence aimed at opponents of the coup, and the cold-blooded killing of which they are targets," it said in a statement in English.
Foreign Affairs Correspondent with Channel 4 News, Jonathan Rugman says the Muslim Brotherhood has planned a week of protests - despite the clampdown by security forces: