BREAKING: The Devolution of The Islamic Revolution in Egypt
Police have fired tear gas in clashes with tens of thousands of protesters gathered near the presidential palace in the Egyptian capital Cairo.
Some of the protesters cut through barbed wire around the palace.
Crowds have been gathering to protest against what they say is the rushed drafting of a new constitution and the decision by President Mohammed Morsi to extend his powers.
Mr Morsi was in the palace but left as the crowds grew, sources there said.
Many of those gathered outside chanted slogans similar to those directed against the regime of former president Hosni Mubarak during protests in February 2011.
Tear gas was fired after protesters managed to breach a barbed wire cordon surrounding the palace, correspondents say.
But the police quickly retreated, allowing protesters to get closer to the palace walls.
Eighteen people were injured in the brief burst of violence but none seriously, the official Mena news agency reported.
In a statement read out on television, Egyptian security forces called for calm among the protesters.
Gee, I hope old Morsi has Obama and Hillary on speed-dial on his cell phone. Hmmm, wonder if it's an Obama Phone?