A mob threw rocks and fired birdshot Sunday at several hundred Christians marching in a protest against Egypt's Islamist government after the funeral of four Christians killed in sectarian clashes over the weekend.

The Christians were chanting slogans against Islamist President Mohammed Morsi, just as several thousand did earlier during the funeral service nearby in the Coptic Orthodox cathedral in Cairo.

The attacking mob, described by witnesses as residents of the area, forced the marchers to take shelter inside the sprawling cathedral complex. They also showered the protesters with rocks from the roofs of nearby buildings, according to witness Ibrahim el-Shareef.

Mohammed Sultan, director of Egypt's national ambulance services, said at least 17 people were wounded in the clashes.


Women grieve at the Saint Mark Coptic cathedral in Cairo for four Christians killed in sectarian clashes on Saturday. (Amr Nabil/Associated Press)

Riot police later arrived, firing tear gas at the Christians and the mob. Several tear gas canisters landed inside the cathedral's grounds, causing a panic among women and children who attended the funeral.

Video footage aired live on the private ONTV network showed young men on the roof of a building adjacent to the cathedral firing handguns in toward the compound.

The four Christians, along with a Muslim, were killed in clashes on Saturday in a town north of Cairo.

Inside the cathedral, several thousand mourners chanted slogans against Morsi, calling on the Egyptian leader to step down. They shouted "Leave!" and "This is our country, we will not leave."

Coptic Christians make up about 10 per cent of Egypt's estimated 90 million people. They have long complained of discrimination. Attacks against Christians have increased since the ouster two years ago of autocrat Hosni Mubarak.