Egyptians last week reacted with outrage after Morsi declared authority over the country's judicial branch. Morsi, elected in June in the country's first democratic vote, assumed legislative authority in recent months. His office said the move is temporary to ensure a new post-revolution constitution is passed.
ElBaradei, once a consideration for the Egyptian presidency, told German news magazine Der Spiegel that not since the pharaohs had anyone wielded such authority over Egypt.
"This is a catastrophe," he said. "It a mockery of the revolution that brought him to power and an act that leads one to fear the worst."
Morsi hails from the Muslim Brotherhood's political arm. Banned under President Hosni Mubarak, the movement has emerged as a dominant political force in Egypt.
ElBaradei echoed sentiments expressed by rival political movements in Egypt who expressed frustration with the Muslim Brotherhood's leadership.
"The country is fractured," he said. "If the moderate forces no longer have a voice, a civil war threatens to erupt in Egypt."
Morsi last week was praised by members of the international community for his work in brokering a cease-fire between Hamas and Israel.