Photo: The Canadian Press. All rights reserved.

Egyptian protesters chant anti-Muslim Brotherhood and Egyptian President Mohammed Morsi slogans outside the presidential palace, background, under a banner with a defaced picture of President Mohammed Morsi and Arabic that reads "the people want to bring down the regime," at the protests site, in Cairo, Egypt, Saturday, Dec. 8, 2012. (AP Photo/Hassan Ammar)

Egypt's opposition said Sunday it will keep up protests against a referendum on a disputed draft constitution but stopped short of advocating either a boycott or a "no" vote less than a week before the ballot.

The opposition was still pushing for Islamist President Mohammed Morsi to cancel the Dec. 15 referendum, saying they reject the process entirely and refuse to call it legitimate.

The referendum over a disputed draft constitution has deeply polarized Egypt and sparked some of the bloodiest clashes between Morsi supporters and opponents since he came to power in June.

In a sign of how jittery the government about holding the referendum, Morsi has ordered the military to maintain security and protect state institutions until the results of the referendum are announced.

The new presidential decree, published in the official gazette, would be effective starting Monday. The military is asked to co-ordinate with the police on maintaining security and would also be entitled to arrest civilians.

Morsi insists on holding the referendum on schedule. Instead, as a concession to his opponents, he rescinded decrees he issued last month granting him almost unrestricted powers, giving himself and the panel that drafted the constitution immunity from judicial oversight.

The decrees sparked the protests. Opponents said they were issued initially to protect the disputed constitution from numerous court challenges.