Egyptian protesters and riot police have clashed in Cairo ahead of a planned rally demanding that President Mohammed Mursi rescinds decrees that granted him near-absolute powers.
The clashes took place near the US Embassy and Tahrir square.
Police fired tear gas after hundreds of protesters threw rocks in a street leading off the square towards the embassy.
The protesters have been staging a sit-in at the square since last Friday night to demand Mr Mursi revoke the decrees.
President Mursi, who has been in power since June, issued a decree expanding his powers and to protect his decisions from judicial review until the election of a new parliament, which is expected in the first half of 2013.
The president said that the decrees are necessary to protect the "revolution" and the nation's transition to democratic rule.
The judiciary has been the main target of Mr Mursi's edicts and they have called the decrees a power grab and an "assault" on the branch's independence.
Egypt's best organised political force, the Muslim Brotherhood has rallied to Mr Mursi's side.
So too have more hardline Islamists who hope the president will keep his promise to implement Islamic laws.
In the opposition stand leftist, liberal and socialist groups that have been consistently beaten at the ballot box by the Islamists since Hosni Mubarak was toppled.
They hope the current crisis will galvanise broader public support.
Elsewhere, the International Monetary Fund's board has indicated that it will require that there is no major change in economic outlook or policy when it considers approving a $4.8bn loan to Egypt.
The loan deal was agreed in principle this month.