Egypt's army deployed tanks outside the presidential palace on Thursday after a night of deadly clashes between opponents and supporters of Islamist President Mohamed Morsi, an AFP correspondent said. At least three tanks and three armoured personnel carriers were stationed outside the front gate of the palace in northern Cairo as hundreds of Morsi backers chanted slogans in support of the president.

Five protesters were killed in the clashes between Islamists and secular-leaning opposition members who said they would escalate protests until Morsi cancels a referendum on a disputed new constitution set for December 15.

Tensions between Islamists and the opposition had been simmering since Morsi adopted exceptional powers on November 22 that allowed him to rush through the constitution, opposed by liberals and Christians, and call the snap referendum.

The overnight violence also spread beyond the capital, with protesters torching the offices of the powerful Muslim Brotherhood in the Mediterranean port city of Ismailiya and in Suez, witnesses said.