Western powers called for restraint and a swift return to democracy in Egypt after the army on Wednesday toppled Islamist president Mohamed Morsi, detaining him and his top aides.
The military said it had responded to mass demonstrations calling on Morsi to go, but the West expressed unease that Egypt's first democratically elected leader had been overthrown after only a year in office.
US President Barack Obama urged a quick return to elected civilian government.
"We believe that ultimately the future of Egypt can only be determined by the Egyptian people," Obama said in a statement after emergency talks with top aides.
"Nevertheless, we are deeply concerned by the decision of the Egyptian Armed Forces to remove President Morsi and suspend the Egyptian constitution."
Obama added that he had ordered a review of the legal implications for US aid to Egypt in the wake of the military's toppling of the elected leader.
In May, Washington renewed its $1.3 billion in annual military aid to Egypt.
UN leader Ban Ki-moon said he understood Egyptians had "deep frustrations" but expressed concern over the army's intervention.
Ban believed that "military interference in the affairs of any state is of concern," deputy UN spokesman Eduardo del Buey said.
The army toppled Morsi after a week of bloodshed that killed nearly 50 people as millions took to the streets, demanding he step down after a turbulent year of rule.
There were fresh reports of deaths early Thursday.
EU foreign policy chief Catherine Ashton condemned the bloodshed.
"I urge all sides to rapidly return to the democratic process, including the holding of free and fair presidential and parliamentary elections and the approval of a constitution," she said.
She hoped the transitional administration announced by the new regime would be fully inclusive and that human rights and the rule of law would be respected, she added.
"I strongly condemn all violent acts...," she added, calling on the security forces to protect all Egyptians.
Egypt's army has confirmed it is holding Morsi and several of his top aides.
Adly Mansour, the little known head of the Supreme Constitutional Court, has been named interim president.
Britain expressed concern at the army's intervention.
"The situation is clearly dangerous and we call on all sides to show restraint and avoid violence," said Foreign Secretary William Hague.
"The United Kingdom does not support military intervention as a way to resolve disputes in a democratic system," Hague said in a statement.
He called for early elections in which all parties could take part and for a civilian-led government.
A Canadian foreign ministry spokesman called for calm, dialogue and a return to democracy.
But Saudi King Abdullah on Wednesday praised the army's intervention and congratulated the new caretaker president Mansour.
"We call on God to help you bear the responsibility to achieve the hopes of our brotherly people in Egypt," the head of the Sunni-ruled oil powerhouse said in his message.
Islamist Sudan said Wednesday it hoped for peace and stability in its "sister" country Egypt, official media reported.
Khartoum was following developments with concern in the hope "that peace and stability shall prevail," the state SUNA news agency said, citing a foreign ministry statement.
London-based rights group Amnesty International said the army had a duty to protect all the country's citizens.
"The armed forces and the police in Egypt have a well-documented record of human rights violations which must not be repeated," it said in a statement.
New York-based Human Rights Watch called on the new administration to "break decisively from a pattern of serious abuses that has prevailed since the January 2011 uprising...".
Both Amnesty and HRW condemned the army's move to shut down pro-Morsi broadcasters as a violation of their right to freedom of expression.