It is claimed as many as 100 supporters of ousted President Morsi have been shot dead by security forces, as William Hague condemns the latest violence in Egypt's capital, Cairo.
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A Muslim Brotherhood website said 120 people had been killed and some 4,500 injured. A Reuters reporter counted 36 bodies at one morgue, while health officials said there were a further 21 corpses in two nearby hospitals.
Egypt's Interior Minister Mohamed Ibrahim accused the Brotherhood of exaggerating the death toll for political ends. He said only 21 people had died and denied police opened fire.
Brotherhood spokesman Gehad El-Haddad said the shootings started shortly before pre-dawn morning prayers after both pro and anti-Morsi supporters held large protests overnight in the capital.
"They are not shooting to wound, they are shooting to kill," Haddad said. The death toll could be more than 100, he claimed.
Above: YouTube footage appears to show how trouble began in Al-Naser street
Foreign Secretary William Hague has called on all sides to end the violence and warned leaders it was their responsibility to reduce tensions following some of the worst scenes since the 2011 uprising that overthrew president Hosni Mubarak.
Hague condemns force
Mr Hague said: "I am deeply concerned by recent events in Egypt, and condemn the use of force against protesters which has led to the loss of lives.
"I call on all sides to refrain from violence. Now is the time for dialogue, not confrontation. It is the responsibility of leaders on all sides to take steps to reduce tensions.
I am deeply concerned by recent events in Egypt, and condemn the use of force against protesters. William Hague
"I call on the Egyptian authorities to respect the right of peaceful protest, to cease the use of violence against protesters, including live fire, and to hold to account those responsible.
"I also call on the Egyptian authorities to release political leaders detained following the events of 3 July, or charge them in accordance with the law. Such charges must be free from any suspicion that they are politically motivated.
"In our view, Egypt needs a political process that includes all groups on an equal footing leading to early and fair elections which all parties are able to contest."
Al Jazeera's Egypt television station reported that 120 had been killed and some 4,500 injured.
A Reuters reporter at the scene counted 36 bodies at a make-shift morgue.
There was no immediate comment from state authorities on what had happened.
If the death toll is confirmed it will make it the deadliest incident since Morsi was deposed earlier this month.
Weeks of violence have followed his ejection, leaving at least 200 dead.
Supporters of deposed Egyptian President Mohammed Morsi carry a protester injured during clashes. (Reuters)
20 dead in Nasr City hospital, our count is 49 dead not counting morgue or other hospitals.— Kareem Fahim (@kfahim) July 27, 2013
Hisham Ibrahim, consultant surgeon at Rabaa, just said he saw around 100 ppl who had died. Not confirmed.— Alastair Beach (@Alastair_Beach) July 27, 2013
Supporters of the Egyptian army prepare to fly a kite painted in the colours of the Egyptian flag from a rooftop during a demonstration at Tahrir Square. (Reuters)
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