Egyptian Vice President Mohamed ElBaradei has strongly condemned the "excessive use of force" in Egypt after deadly clashes between supporters of ousted president Mohamed Morsi and security forces.
"I strongly condemn the excessive use of force and the deaths, and I am working hard and in every direction to end the confrontation in a peaceful way, God protect Egypt and have mercy on the victims," he said on his Twitter account on Saturday.
Condemnation also came from the sheikh of Al-Azhar, Sunni Islam's top authority.
"The sheikh of Al-Azhar deplores and condemns the deaths of a number of martyrs who were victims of today's events," Ahmed al-Tayyeb, who heads the Cairo-based Al-Azhar, said in a statement.
The grand imam called for an "urgent judicial investigation" and punishment of those responsible "regardless of their affiliation".
The statements came after dozens of Morsi supporters were killed in the early hours of Saturday at a long-running protest calling for the reinstatement of Morsi, who was ousted in a military-led coup on July 3.
Witnesses accused security forces of using live fire, but the interior ministry said only tear gas was fired at demonstrators.
Morsi's camp said more than 100 people were killed, while the health ministry said 72 people were killed, and 292 injured in Nasr City.
Mohamed Adel, a member of the April 6 youth movement political bureau, told Al Jazeera that the movement condemns the killing of protesters, and calls for the removal of the interior minister.
The April 6 movement participated in several protests against the deposed president, and criticised his policies.
Meanwhile the National Salvation Front released a statement, expressing "deep sadness" for the deaths of Egyptian citizens in the clashes.
It went on to condemn the Muslim Brotherhood for gathering its supporters at Rabaa Al Adawiyeh Mosque for the past month and "inciting its supporters to attack private and public properties, threatening the lives of Egyptian citizens".
"The Muslim Brotherhood is convincing its supporters they will be honoured by gaining 'shahada' [dying for the sake of God], if they participate in these hostile attacks."
The movement went on to call for an independent judiciary committee to investigate the events.
The Brotherhood, meanwhile, accused the Egyptian military of having "crossed all red lines [...] they killed men, women and children. They arrested thousands of people", according to spokesperson Gihad El-Haddad.
"There is no meeting ground. This is a zero-sum equation. It's either us or them in the equation. It's either we fully reverse this military coup, and continue back into constitutional legitimacy, or we die trying," he told Al Jazeera.
Secretary of State John Kerry said Egypt is at "a pivotal moment" more than two years since the uprising ousted the longtime President Hosni Mubarak.
Kerry said the "final verdict" of the revolution that brought Morsi to power as Egypt's first democratically elected leader before the military recently toppled him "will be forever impacted by what happens right now".
He added that Egyptian officials "have a moral and legal obligation" to respect the right of peaceful assembly and freedom of expression.
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He said the continued violence sets back efforts of "reconciliation and democratisation," and affects regional stability.
The European Union said it deplored the loss of life in Egypt and was following developments there with concern after the deadly clashes.
EU foreign affairs head Catherine Ashton said the authorities should ensure a speedy transition to civilian rule and repeated demands that political detainees, including Morsi, should be released.
A spokesman said Ashton "deeply deplores the loss of life".
Ashton called on all sides to avoid violence, stressing that the "only solution is a rapid move to an inclusive transformation process", adding that "all political groups", including Morsi's Muslim Brotherhood, must be involved.
Turkish Prime Minister Recep Tayyip Erdogan condemned the violence, saying "In Egypt, democracy was massacred, national aspirations were massacred, and now the nation is being massacred."
"Those who remain silent in the face of this massacre have blood on their hands and on their faces," said Erdogan, whose ruling party has close ideological ties with Morsi's Muslim Brotherhood.