Egyptian president Mohammed Morsi has been removed from office in response to the civil unrest that has rocked the country.
The head of Egypt’s army announced on TV that the constitution had been suspended.
The army chief said the president had "failed to meet the demands of the Egyptian people".
US President Barack Obama said he was "deeply concerned" by the latest turn of events and has called for a swift return to civilian rule.
The Australian government on Wednesday increased its travel warning to Australians visiting Egypt.
Foreign Minister Bob Carr raised the travel warning for Australians to the second-highest level: "reconsider your need to travel" after days of strife that have led to deadly clashes.
Anger had been growing against the president and the Muslim Brotherhood – the party from which he comes.
The BBC said protesters were angry at the lack of development in post-revolution Egypt – they accuse the Brotherhood of trying to protect its own interests and of pushing an Islamist agenda.
Australia’s foreign minister advised: "Australians thinking of travelling to Egypt should postpone their trip, and those already there should consider departing."
