Four of the protesters were shot to death.
Another four protesters died of asphyxiation after tear gas canisters were fired at them.
Police, backed by armored vehicles, began attacking protesters with tear gas and rubber bullets on Saturday to disperse the crowds in the square.
And on Saturday, three people were killed during clashes in Liberation (Tahrir) Square.
According to a statement issued by Egypt's Interior Ministry, 55 protesters have been arrested since Saturday.
Meanwhile, the country's military council has threatened protesters with a tougher response if they continue their demonstrations.
The protesters are demanding a speedy transition of power to a civilian government.
Earlier this month, Egyptian Deputy Prime Minister Ali al-Silmi showed a draft copy of a revised constitution to political groups in the North African country. The draft would give the military exclusive authority over its internal affairs and budget and would also shield the armed forces from legal scrutiny.
Activists and political groups are becoming increasingly vocal in their criticism of the failure of the ruling Supreme Council of the Armed Forces (SCAF) to live up to their promise to hand over power to a civilian ruling structure within six months of the February revolution.
Protesters have also censured the chairman of the council, Field Marshal Hussein Tantawi, for his reluctance to implement sweeping change and dismantle elements of the former regime.