Egypt's government has temporarily given the military the authority to arrest civilians to help safeguard a constitutional referendum planned for Saturday, the official gazette said.

The order, which a presidential official and military source confirmed appeared in the gazette late on Sunday, said the military would support police and liaise with them to protect "vital institutions" until a referendum result is declared.

The decree gave army officers the right to make arrests and transfer detainees to prosecutors.

Despite its limited nature, the edict will revive memories of Hosni Mubarak's emergency law, also introduced as a temporary expedient, under which military or state security courts tried thousands of political dissidents and Islamist militants.

A cabinet source said ministers had reviewed the decree last week, saying troops had secured elections during a military-run transition after Mubarak, but with a civilian president now in charge they needed a decree to allow them to play that role.

On Saturday, the military urged rival political forces to solve their disputes via dialogue and said the opposite would drag the country into a "dark tunnel", which it would not allow.

A statement issued by the military spokesman and read onstate radio and television made no mention of President Mohammed Morsi, but said a solution to the political crisis should not contradict "legitimacy and the rules of democracy".

A military source close to top officers said the statement"does not indicate any future intervention in politics".

A military council ran Egypt for 16 months after a popular revolt ended Mubarak's 30 years of military-backed rule last year. The armed forces have not intervened in the latest crisis.

The army statement said the military's duty was to protect national interests and secure vital state institutions.

"The armed forces affirm that dialogue is the best and only way to reach consensus," it added. "The opposite of that will bring us to a dark tunnel that will result in catastrophe and that is something we will not allow."

Hassan Abu Taleb of the Al Ahram Center for Political and Strategic Studies said Saturday's army statement suggested the military wanted both sides to talk out their differences, but discounted the chance of direct military intervention.

"They realize that interfering again in a situation of civil combat will squeeze them between two rocks," he said.