More than 50 people are killed as supporters of the country's ousted president protest during Army celebrations.
The figure, from a health ministry official, comes as Morsi supporters protested in several cities during army celebrations to mark the anniversary of the 1973 Arab-Israeli war.
Hundreds of people are also reported to have been wounded.
A heavy security presence with tanks and armoured vehicles gathered in Cairo to try to deter the protesters, said Trew.
Supporters of Mr Morsi and his Muslim Brotherhood movement had tried to get close to Tahrir Square, where in the past thousands have set up camp in protest against the army's coup.
But security forces guarded entrances to the square, frisking people arriving for the celebrations.
Mr Morsi, who became Egypt's first democratically elected president, was removed from office in July.
Since then, the military-backed government of General Abdel Fatah al Sisi has cracked down on members of the Brotherhood.
Hundreds of Mr Morsi's supporters were allegedly killed in August as protest camps were cleared, while the government said around 100 members of the security forces also died.
Away from the main squares, Cairo's streets were largely deserted on Sunday, a public holiday to commemorate the October War, known as the Yom Kippur War in Israel.
The conflict is remembered proudly by the Egyptian army because it caught Israel by surprise and led to the recovery of the Sinai Peninsula in a 1979 peace treaty.
Supporters of the Army regime waved flags as warplanes flew over Cairo in a show of force and patriotic songs boomed out from loudspeakers.