At least 34 people have been killed in an attack outside the headquarters of the Republican Guard in Cairo, an Egyptian Health Ministry official has said.

Egyptians were on edge today after supporters and opponents of ousted president Mohammed Morsi fought overnight street battles that left at least 30 dead across the increasingly divided country.

Tens of thousands of Islamists have streamed across a Nile River bridge towards Cairo’s Tahrir Square, threatening a showdown.

Egyptian troops have opened fire on protesters marching in support of ousted president Mohammed Morsi, killing at least one and wounding several more.