According to eyewitnesses at least three protesters have been killed outside the Republican Guard barracks in Cairo, where deposed President Mohammed Mursi is being held.
Reportedly troops shot into the air and then at Mursi supporters as crowds grew and pressed forward.
However, a spokesman for the army said only blank rounds and teargas had been fired. It was unclear whether security forces units other than army troops were also present.
A journalist with the Reuters news agency who was on the scene reported seeing at least eight demonstrators who had been hit by shotgun pellets.
The incident occured as hundreds of members of the Muslim Brotherhood movement approached the military cordon.
They were taking part what the Brotherhood has called a “Friday of Rage” to protest against Mursi’s ouster. It is calling for the immediate release of those held by the miltary.
Away from the capital, there were clashes reported between troops and Mursi supporters in three cities on Friday – El-Arish in North Sinai and Suez and Ismailia on the Suez Canal.
Protesters tried to enter government buildings in all three towns according to eyewitnesses. Some threw rocks and troops responded by shooting in the air and firing teargas into the crowds, security sources said.
Thousands of Islamists took to the streets in the cities of Alexandria and Assiut to join protests, opposing a planned interim government which is backed by their liberal opponents.
Egypt’s liberal coalition issued an “urgent call” for its supporters to take to the streets in response to the Islamist protests.
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