A top aide to Egypt's President Mohammed Morsi slammed what he called a "military coup" on Wednesday, July 3, as an army ultimatum passed and the security forces slapped a travel ban on the Islamist leader, AFP reported.

"For the sake of Egypt and for historical accuracy, let's call what is happening by its real name: Military coup," Essam al-Haddad, Morsi's national security adviser, said in a statement on Facebook.

As tension mounted and crowds poured into the streets to demand Morsi's resignation, Haddad said: "As I write these lines I am fully aware that these may be the last lines I get to post on this page."

The announcement came after Morsi proposed a "consensus government" in a last-ditch bid to end Egypt's worst crisis since the 2011 revolution that overthrew dictator Hosni Mubarak.

"The presidency envisions the formation of a consensus coalition government to oversee the next parliamentary election," Morsi's office said on Facebook.

Tens of thousands of people massed in Cairo's Tahrir Square for an anti-Morsi protest that dwarfed a rally by the embattled president's supporters in Nasr City, on the opposite side of the capital.

The interior ministry warned police would respond firmly to any further violence on Wednesday as the armed forces took up positions around key Cairo installations, including the state broadcaster.

Opponents accuse Morsi, Egypt's first democratically elected president, of having betrayed the revolution by concentrating power in Islamist hands and of sending the economy into freefall. His supporters say he inherited many problems, and that he should be allowed to complete his term, which runs until 2016.