US Secretary of State John Kerry led the widespread global condemnation Wednesday of Egypt's bloody crackdown on supporters of ousted president Mohamed Morsi, branding the events in Cairo "deplorable."

The United States did not initially criticize the overthrow of Morsi, Egypt's first democratically elected and Islamist leader, and has avoided using the term "coup," which under US law would have halted some $1.3 billion in annual military aid to Cairo.

But Kerry's comments, in which he called for elections, appeared to fully recant his previously expressed support for Egypt's military-backed government, on which he had recently backtracked.

"Today's events are deplorable and they run counter to Egyptian aspirations for peace, inclusion and genuine democracy," Kerry told reporters.

"The interim government and the military -- which together possess the preponderance of power in this confrontation -- have a unique responsibility to prevent further violence and to offer constructive options for an inclusive peaceful process across the political spectrum.

"This includes amending the constitution and holding parliamentary and presidential elections, which the interim government itself has called for," he said.

Kerry said a political solution was the only option, but acknowledged: "It has been made much, much harder and much, much more complicated by the events of today."

The United Nations, the European Union, Britain, France, Iran, Qatar and Turkey strongly denounced the use of force by the military-backed interim government to clear two protest camps in Cairo.

The action, which was followed by the declaration of a month-long state of emergency, has resulted in at least 278 deaths -- including 43 policemen -- according to Egyptian officials.

UN Secretary General Ban Ki-moon, who had urged both sides to exercise restraint, expressed regret that "Egyptian authorities chose instead to use force to respond to the ongoing demonstrations," according to a statement by his spokesman.

Earlier, White House spokesman Josh Earnest said the United States "strongly condemns" the violence against protesters and urges the military to show restraint.

British Foreign Secretary William Hague said he was deeply concerned at the escalating violence and unrest.

"I condemn the use of force in clearing protests and call on the security forces to act with restraint," Hague said.

European Union foreign affairs chief Catherine Ashton, in a sharpened statement, urged Egypt's rulers to end a month-long state of emergency imposed in the wake of the crackdown.

"I call on the security forces to exercise utmost restraint and on the interim government to end the state of emergency as soon as possible, to allow the resumption of normal life," Ashton said.

"I strongly condemn the violence that has erupted in Cairo and throughout Egypt," she added.

Swedish Foreign Minister Carl Bildt tweeted: "Main responsibility with regime forces. Extremely hard to restore political process."

Qatar, a main backer of the Muslim Brotherhood, Morsi's main constituency, issued a similar message.

"Qatar strongly denounces the means by which peaceful protesters in Rabaa al-Adawiya camp and Al-Nahda square have been dealt with and which led to the killing of several unarmed innocent people among them," a foreign ministry spokesman said.

Turkey -- which had cultivated strong ties with Morsi's government -- urged the international community to act immediately over what it said was an "unacceptable" response to the protests.

Iran termed the crackdown a "massacre."

"Iran is following the bitter events in Egypt closely, disapproves of the violent actions, condemns the massacre of the population and warns of the serious consequences," the foreign ministry said.

The Islamist movement Hamas, the Palestinian branch of the Muslim Brotherhood which rules Gaza, also strongly denounced the crackdown.

"We call for an end to the bloodshed and to excesses against peaceful demonstrators," its spokesman Sami Abu Zuhri told AFP.

France, Germany and Italy refrained from apportioning blame for the crisis, calling for calm from both sides.

"France condemns most resolutely the bloody violence in Egypt and demands an immediate halt to the crackdown," said Foreign Minister Laurent Fabius.

He urged the United Nations and its partners to quickly take a joint stand on the crackdown.

Italian foreign minister Emma Bonino said she was profoundly saddened by events in Egypt.

"I ask all those involved in Egypt to do everything in their power to put an immediate stop to the violence and avoid a bloodbath. The armed forces must exercise the utmost self-control and everyone must avoid any incitement to violence," she said.

German Foreign Minister Guido Westerwelle said: "All further bloodshed must be prevented."

Russia also "called on all political forces ... to show restraint and calm ... in order to avoid a further escalation and further loss of life."