At least 90 people have been killed in Egypt during clashes between protesters and security forces, according to medical sources and eyewitnesses.

At least 54 people were killed in Cairo's Ramses Square, a doctor at a nearby field hospital told an Ahram Online correspondent. The square in downtown Cairo was the intended destination for a number of protest marches called for by supporters of ousted president Mohamed Morsi, after violent dispersals of pro-Morsi sit-ins in Cairo on Wednesday.

Protest marches in several cities across Egypt also turned violent. Local medical sources and eyewitnesses told Ahram Online eight protesters were killed in clashes in the Mediterranean town of Damietta, ten in Fayoum south of Cairo, 11 in the Suez Canal city of Ismailiya, and five in Al-Arish in north Sinai. In addition, eyewitnesses confirmed to Ahram Online three deaths in Alexandria and four in Mansoura in the Nile Delta.

A police conscript was also killed in a drive-by shooting on a security checkpoint north of Cairo, state news agency MENA reported. Citing a security source, Reuters said 24 policemen had been killed and 15 police stations attacked since late Thursday 

There were nationwide protests in Egypt on Friday called for by the Muslim Brotherhood and its allies after a bloody crackdown on Morsi supporters on Wednesday left over 600 dead.

Official health ministry sources put the figure at 27 nationwide on Friday evening.

Western nations, including the US, Germany and France, have urged restraint and condemned the violence, but Saudi Arabia's King Abdullah said his country stood with Egypt in its battle against "terrorism.”