US President Barack Obama joined in global condemnation Thursday of Egypt's military rulers over the bloody crackdown on Muslim Brotherhood protesters, while France warned of the threat of "civil war" and the UN rights chief demanded an investigation.
More than 500 people were killed in Wednesday's assaults on two Cairo protest camps of supporters of ousted Islamist president Mohamed Morsi, in the country's worst violence in decades.
Paris, London, Berlin, Rome and Madrid summoned Egypt's ambassadors to voice their strong concern.
Obama said Washington "strongly condemns" the military action, warning that Egypt had entered a "more dangerous path" and announcing the cancellation of US military exercises with Egypt.
He bemoaned the "violence that has taken the lives of hundreds of people and wounded thousands more" but stopped short of suspending $1.3 billion in annual military aid to Egypt, which has for decades been a key regional ally of the United States.
The United States did not initially object to the overthrow of Morsi -- Egypt's first democratically elected and Islamist leader -- and has avoided using the term "coup," which would require it cut assistance.
UN rights chief Navi Pillay said the death toll points "to an excessive, even extreme, use of force against demonstrators".
"There must be an independent, impartial, effective and credible investigation of the conduct of the security forces," she said. "Anyone found guilty of wrongdoing should be held to account."
Pillay urged "all sides in Egypt to step back from the brink of disaster."
Turkey's Prime Minister Recep Tayyip Erdogan, a Morsi supporter, called for an urgent UN Security Council meeting over Egypt's "massacre".
China was characteristically muted, appealing for "maximum restraint" from all parties, while fellow Security Council permanent member Russia only urged tourists to avoid trips to Egypt.
Only two Gulf states that have cracked down on Islamist groups within their own borders, the United Arab Emirates and Bahrain, voiced support for the Cairo military leaders.
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French President Francois Hollande said "everything must be done to avoid a civil war" and called for new elections, while his government conveyed France's "great concern over the tragic events" to Egypt's envoy.
Britain also condemned the violence and expressed its "deep concern" to Cairo's ambassador.
Germany, whose Foreign Minister Guido Westerwelle has called for an end to violence and resumed negotiations, told Egypt's envoy its position "in no uncertain terms," said a ministry spokeswoman.
Turkey's Erdogan criticised the "silence" of the global community in the face of the bloodshed.
"This is a very serious massacre... against the Egyptian people who were only protesting peacefully."
Pope Francis said he was praying for the victims of the violence and appealed for "peace, dialogue and reconciliation."
Denmark suspended aid worth four million euros ($5.3 million) to Egypt "in response to the bloody events and the very regrettable turn the development of democracy has taken".
Norway's Foreign Minister Espen Barth Eide said the situation in Egypt "has all the characteristics of a military coup."
From Asia, Pakistan expressed its "dismay and deep concern" over the loss of innocent lives and called the events "a major setback for Egypt's return to democracy."
The Philippines urged its 6,000 nationals in Egypt to leave the country and raised the alert level due to the "escalating civil unrest."
Only the United Arab Emirates and Bahrain voiced support for Egypt's military leaders, saying it was the state's duty to restore order.
The Emirati foreign ministry affirmed its "understanding of the sovereign measures taken by the Egyptian government after it had practised maximum self-restraint during the preceding period".
Bahrain, which is facing an uprising led by the Shiite majority against the Sunni regime, said that the "measures taken by Egyptian authorities to restore peace and stability were to protect the rights of the Egyptian citizen, which the state is obliged to do."