Tens of thousands of Egyptians are holding a rally in Cairo to protest against Egypt's military rulers.
Demonstrators from across the political spectrum have gathered in Tahrir Square after the military council proposed controversial constitutional changes.
Many Egyptians fear the military is trying to entrench its power.
Egypt has been ruled by a military council since President Hosni Mubarak was ousted in February. Parliamentary elections are due this month.
The protest, and another in Egypt's second city, Alexandria, are demanding the withdrawal of proposals for constitutional change by the military authorities.
The cabinet wants to declare the military the guardian of "constitutional legitimacy". Critics say the wording suggests the armed forces could have the final word on major policies even after a new president is elected.
The document also introduces clauses that would shield the military from civilian oversight.
Our correspondent says there is also widespread frustration in Egypt that, despite the overthrow of Mr Mubarak, life for the majority is not improving.
However, it is the conservative Islamists of the Muslim Brotherhood who are most vocal in these demonstrations rather than the young people using social networks who led the protests earlier this year, he says.
Witnesses say that Tahrir Square was split between the Brotherhood's Freedom and Justice Party and the more hardline Islamist Salafi rivals, represented by several political parties.
The two set up separate stages and organised their own speeches and chants, only joining forces for Friday prayers.
The Brotherhood has so far avoided confrontation with the ruling military Supreme Council but is now warning that protests will escalate if plans to give permanent political powers to the military are not scrapped.
"The army has no role in ruling people," said Hani Hegazi, 28, a Brotherhood member in the Cairo protest.
"Its only job is to protect the country. We want civilian rule chosen through democracy."
In Tahrir Square - the symbolic heart of the uprising that toppled President Mubarak - people waved banners reading: "Down with military rule" and "Egypt our country is not a military camp".
In Alexandria, thousands of Islamists and members of youth groups planned to head to a military base in a show of protest against the army.
The Muslim Brotherhood is Egypt's most organised political group and is expected to perform well in elections due on 28 November.